We recommend replacing tyres at 3mm — well above the legal 1.5mm minimum. Here's why the difference matters enormously on NZ's wet roads:

At 1.5mm, a tyre at 80 km/h needs 18 metres more to stop than at 8mm — that's roughly 4 car lengths. In Bay of Plenty and Waikato where rain is frequent and roads are often chipseal, grip deteriorates rapidly below 3mm.

🛑 Braking Distance Calculator — see how tread depth affects YOUR stopping distance | ✅ WOF Tyre Guide

The NZ 20-cent coin test is the quickest way to check tread depth without a gauge:

1. Take a New Zealand 20-cent coin

2. Insert it into the main tread groove with the number "20" facing down into the groove

3. If you can see the entire "20", your tread is at or below approximately 2mm — time to replace

4. If the "20" is partially hidden by the tread, you still have usable depth

Important: Check at least 3 points across the tread width (inner edge, centre, outer edge) and at multiple points around the tyre. Uneven wear can mean one spot is at 2mm while another is at 5mm.

For more accuracy: A proper tread depth gauge costs $5–15 from any auto parts store and reads to 0.5mm precision. Worth having in the glovebox alongside your tyre pressure gauge.

✅ WOF Tyre Guide — see exactly what inspectors measure and where

Same test as above — the "20c test" is just the common shorthand NZ drivers use.

The NZ 20-cent coin has a diameter of approximately 21mm. The "20" numeral sits roughly 2mm from the rim edge. When the entire "20" is visible above the tread, you're at approximately 2mm depth — below our recommended 3mm replacement threshold and approaching the 1.5mm legal minimum.

Limitations of the coin test:

• It only tells you "above or below ~2mm" — not the exact depth

• It can't detect internal damage, cracking, or belt separation

• Tyre wear indicators (TWI bars) moulded into the grooves are more reliable — when tread is flush with these bars, you're at 1.6mm

For a precise reading, ask at any tyre shop or use a $10 digital tread gauge. Most shops will check for free.

Increase rear tyre pressure by 4–8 PSI above your vehicle's standard recommendation when towing. The exact increase depends on tongue weight and gross trailer mass.

Why: Tongue weight transfers 10–15% of trailer weight onto your rear axle. Under-inflated rears under towing load causes excessive sidewall flex, heat buildup, and in severe cases, blowout risk.

Never exceed the maximum pressure stamped on the tyre sidewall. Check your vehicle's door placard — many list separate pressures for "loaded" or "towing" conditions.

🎯 PSI Calculator — find your ideal pressure | 🔧 Towing Load Calculator

Increase all tyre pressures by 2–6 PSI when carrying heavy loads. Most vehicle door placards show two settings: "normal" and "full load."

General rule: For every 100 kg added above standard occupancy, increase pressure by approximately 2 PSI on the loaded axle, up to the tyre's maximum sidewall pressure.

Common heavy-load NZ scenarios:

• Ute with loaded tray: Rear +4–8 PSI depending on weight. A Hilux with 500 kg in the tray needs significantly more rear pressure.

• Family road trip (5 adults + luggage): All tyres +2–4 PSI above normal

• Moving house: Heavily loaded — use the "full load" placard setting

• LT tyres on commercial vehicles: Follow the load/inflation table specific to your tyre's ply rating. LT tyres can run up to 65–80 PSI at maximum load.

After unloading: Return to standard pressures. Running heavy-load pressures on an empty vehicle causes centre-strip wear and a harsh ride.

🎯 PSI Calculator — accounts for load adjustments

Drop pressure by 4–6 PSI below your highway setting for sustained gravel driving. This isn't just about comfort — it protects against punctures and chipping.

Why lower pressure helps on gravel:

• Larger contact patch — spreads load over more stones, reducing the force per stone trying to puncture your tread

• Better absorption — softer tyre absorbs corrugation impacts instead of bouncing

• Reduced stone chipping — less impact force means fewer chips gouged from the tread

• More traction — tyre moulds around loose surfaces rather than sitting on top

Typical gravel settings (passenger/SUV):

• Highway: 32–36 PSI → Gravel: 28–30 PSI

• LT tyres: Highway 50–60 PSI → Gravel: 40–45 PSI

Re-inflate before returning to sealed roads. Running gravel pressures at highway speed causes excessive heat buildup and accelerated wear.

📖 4WD Tyre Guide — terrain-specific pressure advice

Typically 15–20 PSI for firm sand, 12–16 PSI for soft sand. This is the single most important factor for beach driving — more so than tyre type or 4WD mode.

⚠️ Below 12 PSI: Risk of the tyre separating from the rim (debeading), especially on low-profile or standard passenger tyres. Only go this low on proper 4WD rims with bead-lock capability or aggressive tread patterns that grip the rim.

NZ beach tips: Muriwai, 90 Mile Beach, and Coromandel beaches all have sections of soft sand. Air down BEFORE you hit the sand — not after you're stuck. Carry a compressor and know how long it takes to reinflate (see Q10).

📖 4WD Tyre Guide

Most standard alloy wheels are safe down to about 15 PSI. Purpose-built 4WD steel wheels can go to 10–12 PSI. The risk isn't tyre damage — it's the tyre popping off the rim (debeading).

Factors that affect minimum safe pressure:

• Rim type: Steel rims with a defined bead seat hold tyres better than smooth alloy rims

• Tyre type: Mud terrain and all-terrain tyres with aggressive sidewall lugs grip the rim better than highway tyres

• Speed: At low speed (under 30 km/h), debeading risk is much lower

• Turning: Sharp turns at low pressure push the tyre sidewall and can roll it off the rim

Bead locks: If you're regularly driving below 12 PSI on sand dunes, bead-lock wheels mechanically clamp the tyre bead to the rim. Essential for competition but overkill for occasional beach driving.

Golden rule: If you hear or feel the tyre squelching on the rim during turns, you're too low. Add 2–3 PSI immediately.

Yes — dropping 4–8 PSI below highway pressure significantly reduces corrugation damage and improves comfort and control.

Why corrugations are damaging at highway pressure: At 35+ PSI on corrugated gravel, tyres bounce rather than absorb. This causes:

• Intermittent traction loss (tyres literally leave the surface)

• Accelerated suspension wear from constant impact

• Stone chip damage to tread from high-impact strikes

• Driver fatigue from vibration

Recommended settings for NZ corrugated roads:

• Passenger/SUV: Drop from ~34 PSI to 28–30 PSI

• LT/4WD: Drop from ~50 PSI to 38–42 PSI

• Keep speed below 80 km/h on gravel regardless of pressure

NZ context: Central Otago, Coromandel backcountry, and most DOC tracks have significant corrugation. The Skippers Canyon road near Queenstown is legendary for destroying tyres at highway pressure.

You need a portable air compressor — petrol stations are rarely near beach access points.

Options for reinflation:

• 12V portable compressor (plugs into cigarette lighter) — most common, $50–200. Takes 3–8 minutes per tyre from 15 to 35 PSI depending on tyre size and compressor quality.

• On-board air system (permanently mounted) — ARB, TJM, or similar. Faster, more reliable, $400–1,200 installed. Essential for frequent off-roaders.

• CO2 inflation kit — instant inflation using compressed CO2 cartridges. Fast but expensive per use ($5–10 per tyre). Good as backup.

• Manual foot pump — works but extremely slow for 4WD tyres. Might take 15+ minutes per tyre. Emergency only.

Critical: Re-inflate to highway pressure BEFORE driving on sealed roads. Driving at beach pressure (15 PSI) on tarmac at 100 km/h causes extreme heat buildup and can blow out the tyre within minutes.

Tip: Air up on the hard sand near the exit, not on the road. It's easier and you can check pressures before hitting traffic.

A tyre deflator is a device that clips onto the valve stem to let air out in a controlled, hands-free way — usually to a preset pressure.

Types:

• Preset deflators (e.g., Staun, ARB): Screw onto all four valves simultaneously, automatically stop at your preset PSI. Set once, deflate all four tyres at once. $60–120 for a set of 4.

• Rapid deflators: Remove the valve core temporarily for fast deflation. Dangerous if you lose the core — carry spares.

• Simple bleed valves: Depress the valve pin manually. Slow and requires constant gauge checking.

Should you use one? If you drive on beaches or gravel more than a few times a year, preset deflators are worth it. They're faster, more accurate, and you can set all four tyres simultaneously while you organise gear.

NZ recommendation: A set of Staun-style deflators + a good 12V compressor is the standard kit for anyone doing 90 Mile Beach, Muriwai, or Coromandel beach driving.

A portable air compressor pumps air into tyres using your vehicle's 12V power or an independent motor. Size matters — an undersized compressor takes forever and overheats.

Key features to look for:

• Direct battery connection (not cigarette lighter) for anything over 40 L/min — the cigarette socket fuse will blow

• Auto shut-off at preset pressure — prevents over-inflation

• Duty cycle: Cheap compressors overheat after 10–15 min and need cooling. Quality units run continuously.

• Accurate built-in gauge — many budget gauges read 2–4 PSI off. Verify with a separate digital gauge.

Yes — rotate every 5,000–6,000 km instead of the standard 8,000–10,000 km. Gravel accelerates uneven wear in two ways:

• Abrasion: Loose stones act like sandpaper, wearing tread faster than sealed roads

• Irregular impacts: Corrugations and stones create uneven forces that promote cupping and scalloping

Rotation pattern depends on your drivetrain:

• 4WD/AWD: Cross-rotation (front-left → rear-right) unless directional tyres

• FWD: Front-to-rear, same side

• RWD: Rear-to-front, crossing over

• Directional tyres: Front-to-back only, same side

NZ rural drivers: If more than 30% of your driving is gravel, rotation at every oil change (~5,000 km) is a good habit. Ask about rotation when you book fitting — most shops include it free with a tyre purchase.

Every 12 months or 15,000 km — whichever comes first. NZ roads are harder on alignment than most countries.

Why NZ needs more frequent alignment:

• Potholes: NZ's road maintenance backlog means more and deeper potholes, especially in Bay of Plenty, Waikato, and Canterbury after heavy rain

• Speed bumps: Many NZ councils have installed aggressive speed bumps that impact suspension geometry

• Gravel roads: If you regularly drive unsealed roads, check alignment every 10,000 km

• Chipseal transitions: Uneven road surface joints can jar suspension components

Signs you need alignment now (don't wait for the schedule):

• Vehicle pulls to one side on a flat, straight road

• Steering wheel is off-centre when driving straight

• Uneven tread wear (one edge wearing faster — see wear pattern section below)

• After any significant pothole hit or kerb strike

Cost: $60–120 for a standard 4-wheel alignment in NZ. Much cheaper than replacing tyres worn out from misalignment.

Yes — always. It's the most cost-effective insurance you can buy for your new tyres.

Why alignment matters with new tyres:

• New tyres with full 8mm tread will show misalignment wear patterns much faster than worn tyres

• Your old tyres may have been compensating for (hiding) existing misalignment

• If alignment is off by just 2mm of toe, you'll scrub 1–2mm of tread in the first 5,000 km

What a good shop does: Print the before and after alignment report showing toe, camber, and caster. Keep this — it's your baseline. If wear appears later, you can compare against the alignment printout to identify what changed.

When you book fitting with us, we can arrange alignment at a partner shop near you.

Five clear symptoms that indicate your wheel alignment needs checking:

• Vehicle pulls left or right on a flat, straight road with hands lightly on the wheel. Test on a flat section — road camber (crown) can cause mild pull that's normal.

• Steering wheel off-centre — the logo or spokes aren't level when driving straight. This is usually a toe misalignment.

• Uneven edge wear — one side of the tread is wearing significantly faster. Inside edge = excess negative camber or toe-out. Outside edge = excess positive camber or toe-in.

• Steering feels vague or wanders — requires constant small corrections to maintain straight-line driving

• Tyres squeal on slow turns — particularly in parking buildings. Toe misalignment causes the tyre to scrub sideways through turns.

After a pothole or kerb hit: Even if you don't feel immediate symptoms, get alignment checked. A bent tie rod or shifted subframe can cause rapid tyre destruction within weeks.

📖 See the Wear Patterns section below for visual diagnosis

Suspension wear creates distinctive tyre wear patterns that alignment alone can't fix:

• Cupping/scalloping — high and low spots around the tread circumference, like a series of shallow scoops. Caused by worn shocks/struts that allow the tyre to bounce rather than maintain consistent contact. Most noticeable at 60–80 km/h as a rhythmic drone.

• Diagonal wear — wear pattern runs diagonally across the tread. Often caused by worn bushings allowing the wheel to shift under load.

• One-side wear that persists after alignment — if alignment readings are correct but one edge keeps wearing, suspect a bent control arm, worn ball joint, or shifted subframe.

• Sagging stance — one corner sits lower than the others. Worn springs change ride height which changes camber angle.

NZ context: Vehicles over 150,000 km in NZ (common given our used-import market) frequently have worn shocks and bushings. New tyres on worn suspension wear out 30–50% faster.

Fix the suspension first — fitting new tyres on worn shocks is throwing money away.

New tyres didn't cause this — they revealed an existing issue. The most common reasons:

• Toe misalignment: Your old tyres had worn into the misalignment and compensated. New tyres with uniform tread expose the true alignment state. Solution: Get an alignment.

• Tyre-to-tyre variation: New tyres may have slightly different rolling diameters or conicity (a manufacturing trait where the tyre naturally pulls slightly in one direction). Try swapping the front tyres left-to-right. If the pull reverses, it's conicity — a warranty issue.

• Steering rack centring: Some shops adjust toe correctly but don't centre the steering wheel first. The alignment numbers look fine on paper, but the wheel is crooked. Ask them to re-centre.

Is it dangerous? A slightly off-centre wheel with correct alignment angles is cosmetic, not dangerous. But if the vehicle also pulls to one side, get it checked promptly — uneven forces wear tyres fast.

Some vibration is normal for the first 100–500 km while tyres bed in. If it persists beyond that, the most likely causes in order of frequency:

• Balancing issue (70% of cases): One or more wheels not properly balanced, or a weight fell off. Return to the fitting shop — rebalancing is usually free within 30 days.

• Tyre seating (15%): The tyre bead hasn't fully seated on the rim. Requires deflating and reinflating, sometimes with bead lubricant.

• Rim damage (10%): A bent or buckled rim that wasn't noticed during fitting. Alloy rims bend from pothole hits and may not be visually obvious.

• Tyre defect (5%): Radial force variation (RFV) — a manufacturing inconsistency that causes the tyre to push harder at one point per revolution. Diagnosed with a road force balancer.

Speed matters for diagnosis:

• 60–80 km/h vibration = usually balance

• 100+ km/h vibration = balance or bent rim

• Vibration at all speeds = tyre defect or severe rim bend

See our Technical Specs FAQ for details on road force balancing and RFV thresholds.

A rhythmic thump-thump-thump at low speed is almost always a tyre issue. Common causes:

• Flat spot: Vehicle sat stationary for days/weeks, creating a temporary flat on the contact patch. Usually warms out after 5–15 minutes of driving. If it doesn't go away, the flat spot may be permanent (requires replacement).

• Belt separation: Internal steel belts have separated from the rubber, creating a raised section or bulge. ⚠️ This is dangerous — the tyre can fail catastrophically. Run your hand around the tread surface feeling for any raised areas or lumps. If found, replace immediately.

• Chopped/cupped tread: Worn shocks cause the tread to wear in a scalloped pattern that thumps at low speed and drones at higher speed.

• Object in tread: A stone, nail, or bolt embedded in the tread can cause a rhythmic thump as it contacts the road surface each revolution.

How to identify which tyre: Drive slowly in a quiet area with windows down. The thump will be louder on the side of the affected tyre. You can also jack up each corner and spin the wheel by hand, looking and feeling for irregularities.

A hum that increases in pitch with speed points to either tyre wear pattern or wheel bearing — here's how to tell the difference:

Wheel bearing test: Swerve gently left and right at 60+ km/h. If the hum changes volume (louder one way, quieter the other), it's a bearing. The bearing on the side the noise reduces when you lean away from it is usually the failed one.

Tyre noise: Cupped or feathered wear from worn shocks or misalignment creates a drone that increases with speed. Aggressive tread patterns (MT, AT) are naturally louder than highway tyres. See our Terrain Types FAQ for noise comparison.

Inside edge wear is the most common alignment-related wear pattern in NZ. The primary cause is excess negative camber — the top of the wheel tilts inward, pressing the inside edge into the road.

Common causes:

• Worn suspension components: Ball joints, control arm bushings, or strut mounts that allow the wheel to tilt inward under load. Very common on NZ-used imports with 100,000+ km.

• Lowered suspension: Lowered vehicles change camber geometry. Without camber correction, inside wear accelerates dramatically.

• Toe-out: When the front of the tyres point outward, the inside edges scrub on every revolution.

• Overloading rear: Heavy loads compress rear suspension, changing camber angle.

Fix: Alignment first. If camber is out of factory spec and can't be adjusted, suspect worn components. On some vehicles (particularly Japanese imports), aftermarket camber bolts or adjustable arms are needed.

Outside edge wear indicates excess positive camber or aggressive toe-in. Less common than inside wear but equally destructive.

Common causes:

• Positive camber: Top of wheel tilts outward — usually from worn springs (sagging ride height) or incorrect lift kit geometry

• Aggressive driving: Hard cornering loads the outside edge heavily. Performance drivers often see this on front tyres.

• Under-inflation: Low pressure causes the tyre to roll onto its outer shoulder during cornering. Check and correct pressures first before assuming alignment.

• Toe-in: When the front of the tyres point inward, the outside edges scrub.

NZ note: Vehicles with non-OEM lift kits (common on Hilux, Ranger, Navara) frequently develop outside edge wear because the lift changes suspension geometry without correcting camber and caster.

🎯 PSI Calculator — check pressures first, then get alignment

Centre-strip wear means your tyres are over-inflated. This is the easiest wear pattern to diagnose and fix.

What's happening: Excess air pressure causes the tread to crown outward, lifting the shoulder edges off the road. Only the centre strip contacts the surface, wearing it faster than the edges.

How much is too much? Running 5–10 PSI above recommended pressure will show visible centre wear within 10,000–15,000 km. Running 15+ PSI over shows it within 5,000 km.

Common causes:

• Reading tyre pressure placard incorrectly (using the MAX sidewall pressure instead of the recommended placard pressure)

• Not adjusting after loading/unloading — running "heavy load" pressures when the vehicle is empty

• Seasonal: Air expands in heat. Tyres inflated to 35 PSI in winter may read 38–40 PSI in summer.

Fix: Set pressures to the door placard recommendation when tyres are cold (haven't driven more than 3 km). Check monthly.

🎯 PSI Calculator — find your correct pressure

Both-edge (shoulder) wear means your tyres are under-inflated. The second most common wear issue we see.

What's happening: Insufficient pressure causes the tread to sag inward, lifting the centre off the road. Both shoulder edges bear the load and wear faster.

The hidden danger: Under-inflation doesn't just waste tread — it generates excessive heat in the sidewall. This is the #1 cause of motorway blowouts. The tyre looks fine externally but the internal structure is being cooked from the inside.

How much does it matter?

• 5 PSI under: +3% fuel consumption, sidewall stress begins

• 10 PSI under: +8% fuel, significant heat buildup, edge wear visible within 5,000 km

• 15+ PSI under: Blowout risk, especially at sustained highway speed in NZ summer

Fix: Check pressures monthly. Most NZ drivers check 2–4 times per year — not enough. Every petrol station has free air.

🎯 PSI Calculator

Cupping (also called scalloping or chopping) creates a wavy, uneven surface with high and low spots around the circumference. It's the wear pattern that makes a drone/hum noise that increases with speed.

Primary causes:

• Worn shock absorbers (most common): The tyre bounces instead of maintaining consistent road contact. Each bounce creates a slightly deeper wear spot. Over thousands of km, this creates a visible wave pattern.

• Imbalanced wheels: Heavy spots create rhythmic pressure variations that carve out high/low points

• Toe misalignment: Slight toe-out on the rear axle causes diagonal feathering that develops into scalloping

• Infrequent rotation: Non-driven wheels (usually rears on FWD) are more susceptible because they follow rather than drive

Can it be fixed? Once established, cupping doesn't wear out — it gets worse. Rotate the affected tyre to the opposite position and fix the root cause (shocks, balance, alignment). Severe cupping requires replacement.

NZ context: Very common on NZ-used imports with 120,000+ km where shocks are original and never replaced.

Yes — over-inflation measurably reduces wet grip. Here's the physics:

An over-inflated tyre crowns outward, reducing the contact patch area by 10–20%. Less rubber on the road means:

• Fewer sipes and grooves in contact to channel water away

• Higher contact pressure per square cm — sounds good but actually causes the tyre to ride on top of the water film rather than cutting through it

• Less mechanical grip from reduced surface area

How much difference? Testing shows that 10 PSI over-inflation can increase wet braking distance by 5–10% — roughly 1–3 metres at 80 km/h. On NZ's frequent wet chipseal roads, where grip is already marginal, this matters.

The other risk: Over-inflated tyres are more susceptible to impact damage. The rigid sidewall can't flex to absorb pothole hits, leading to bruising, belt separation, and sudden air loss.

🛑 Braking Distance Calculator — see how grip rating affects stopping

Yes — under-inflation is the #1 cause of tyre blowouts on NZ motorways.

The failure mechanism:

1. Low pressure → excessive sidewall flexing with each revolution

2. Flexing generates internal heat (the sidewall is being bent back and forth hundreds of times per km)

3. Heat weakens the bond between rubber layers and steel belts

4. Internal structure delaminates — the layers separate

5. Weakened area can no longer contain air pressure → sudden catastrophic failure

How fast does it happen? A tyre at 20 PSI (vs recommended 32 PSI) driven at 100 km/h on a hot NZ summer day can reach internal temperatures of 120°C+ within 30 minutes. The rubber-to-steel bond begins failing at ~110°C.

Warning signs before blowout:

• Both-edge shoulder wear pattern

• Sidewall cracking or bulging

• Vehicle feels "spongy" or wanders at highway speed

• TPMS warning light (if equipped)

Check pressures monthly. It takes 60 seconds and could save your life. 🎯 PSI Calculator

Only for very short distances at low speed to reach a tyre shop. A slow puncture is still a puncture — the tyre is losing structural integrity.

Risk assessment:

• Losing 1–2 PSI per day: You can likely drive to a shop the same day if you top up air first. Check visually before driving — if the tyre looks even slightly flat, don't drive on it.

• Losing 5+ PSI per day: The object may be working loose. The hole could enlarge suddenly. Drive directly to the nearest tyre shop, stay under 60 km/h.

• Visibly low or flat: Do not drive. Even 1 km on a flat tyre can destroy the sidewall and inner liner, turning a $30 repair into a $150+ replacement.

If you must drive: Top up air, drive under 60 km/h, avoid motorways, keep the journey under 10 km, and avoid hard braking or cornering. If you hear any unusual sounds — stop immediately.

See our Puncture Repairs section for what can and can't be repaired.

If the tyre is holding air: get to a shop within 24 hours. If it's flat: zero kilometres — don't drive.

With a nail/screw still in place and tyre holding pressure: The object is actually sealing the hole. You may be able to drive normally for days. But the longer you wait, the higher the risk of:

• The object working loose and rapid air loss

• Water and road debris entering the hole and corroding steel belts

• The hole enlarging beyond repairable size (max 6mm)

On a flat or near-flat tyre:

• 0–1 km at walking speed: The inner liner is being ground between the rim and road. Damage escalates with every metre.

• 1–5 km: Inner liner destroyed, sidewall damaged. The tyre is now unrepairable regardless of puncture location.

• 5+ km: Structural failure likely. The rim may also be damaged.

Run-flat tyres: Designed for up to 80 km at 80 km/h after complete pressure loss. Standard tyres have no such capability. See Run-Flat FAQ.

Stop when safe and inspect immediately. Even a single hard hit can cause invisible internal damage that leads to failure hours or days later.

Immediate checks:

• Visual: Look for bulges, cuts, or deformation on the sidewall (the area between the tread and rim). Any bulge = internal structure failure = replace immediately.

• Pressure: Check air pressure. If it's dropped more than 3–5 PSI within an hour of the hit, you may have a slow leak from rim damage or bead unseating.

• Rim: Look for dents, cracks, or deformation on the rim lip. Alloy rims crack; steel rims bend.

• Vibration test: Drive slowly and feel for new vibrations or pulling. Any change in handling = get inspected.

NZ pothole reality: Bay of Plenty, Waikato, and Canterbury roads after winter have notorious pothole problems. If you hit a deep one at speed, get the tyre and rim inspected at a shop — internal belt damage isn't visible from outside.

Not always — but you need a professional inspection. Whether to replace depends on what damage occurred:

Must replace if:

• Any sidewall bulge (even small — this is a structural failure)

• Visible sidewall cut exposing cords

• Rapid air loss that won't hold pressure after reinflation

• Rim is cracked (alloy) or severely bent (steel)

Probably OK if:

• No visible damage after thorough inspection

• Air pressure holds for 24+ hours

• No new vibration at highway speed

• Rim shows no deformation

Hidden risk: Internal belt separation from impact may not show symptoms for weeks. If you hit a severe pothole, consider getting the tyre inspected from the inside by removing it from the rim — a good shop can do this during a rotation or balance.

Pull over safely (use the next exit or rest area — never stop on the motorway shoulder unless you have to) and inspect all four tyres plus the underside.

What to look for:

• Embedded objects: Nails, screws, wire, glass, metal fragments. Don't remove them — they're often sealing the hole. Drive to a shop.

• Cuts or gashes: Run your hand carefully around the tread and sidewall. Feel for any cuts, especially if you can see cords (the fabric or steel internal structure).

• Chunks missing: Debris can gouge chunks from the tread. Small surface chunks (under 5mm deep) are cosmetic. Deep chunks exposing belt material require replacement.

• Pressure loss: Use a gauge if you have one, or visually compare all four tyres for any that look lower.

• Underside damage: Debris can damage brake lines, suspension components, or the underfloor. Look for any hanging or dragging parts.

NZ motorway tip: State Highway 1 through Hamilton, Tauranga, and Auckland has frequent debris. Keep a pressure gauge and small torch in the glovebox.

Do NOT brake hard. Do NOT swerve. Here's the correct response that could save your life:

Step-by-step:

1. Grip the steering wheel firmly with both hands. A blowout will try to pull the vehicle to the side of the failed tyre. Resist the pull but don't overcorrect.

2. Do NOT slam the brakes. Hard braking with a blown tyre causes the vehicle to pivot around the deflated corner. This is how blowout accidents become rollovers.

3. Gently apply the accelerator for 2–3 seconds to maintain stability and forward momentum. This sounds counterintuitive but helps maintain a straight trajectory.

4. Gradually ease off the accelerator. Let the vehicle slow naturally through rolling resistance.

5. Signal and steer gradually toward the shoulder. Only apply gentle braking once you're below 50 km/h and on the shoulder.

6. Stop well clear of traffic. Turn on hazard lights. Exit the vehicle on the side away from traffic.

After stopping: Do not attempt to change the tyre on a motorway if you're on the narrow shoulder. Call roadside assist. Your life is worth more than a tyre.

Ease off the accelerator, hold the wheel straight, and do NOT brake. Aquaplaning means your tyres are riding on a film of water with zero road contact.

Step-by-step:

1. Lift off the accelerator smoothly — don't jerk your foot off

2. Keep the steering wheel pointed straight — don't try to steer. With no traction, steering inputs do nothing until grip returns, then cause a violent swerve.

3. Do NOT brake — locked wheels on water = zero control. Even ABS can't help on a full aquaplane.

4. Wait for grip to return. As speed drops, the tyres will break through the water film. You'll feel the steering "wake up" — usually within 2–4 seconds.

5. Once grip returns, gently steer and brake as needed.

Prevention:

• Maintain tread depth above 3mm (see Q1 — at 1.5mm, aquaplaning starts at 65–70 km/h)

• Reduce speed in standing water — even good tyres aquaplane at 80+ km/h in deep water

• Follow wheel tracks of the vehicle ahead — they've already displaced water from that path

• Avoid cruise control in rain — it prevents you from feeling the first loss of traction

🛑 Braking Distance Calculator — see how wet conditions affect stopping

Not always — ABS primarily maintains steering control during hard braking, which is even more important than distance.

What ABS actually does: Rapidly pulses the brakes (up to 15 times per second) to prevent wheel lock-up. Locked wheels slide — unlocked wheels can still steer.

On wet sealed roads: ABS typically stops in about the same distance as a skilled driver threshold braking. For most drivers (who instinctively slam and lock brakes), ABS reduces wet stopping distance by 10–30%.

On gravel: ABS can actually increase stopping distance. Locked wheels on gravel build a wedge of material in front that helps slow the vehicle. ABS prevents this wedge. Some 4WDs have a "gravel mode" ABS setting for this reason.

On ice: ABS helps enormously — locked wheels on ice have almost zero friction, while rolling wheels maintain some directional control.

The real benefit: You can brake AND steer simultaneously. Without ABS, hard braking = no steering. With ABS, you can brake hard while swerving around an obstacle.

Typically 30–60% longer on wet roads, depending on tread depth and tyre quality.

NZ-specific: Freshly laid chipseal with loose aggregate in wet conditions is the worst-case scenario — grip levels approach those of ice. Bay of Plenty and Waikato roads are frequently re-sealed and NZ's maritime climate means rain is never far away.

🛑 Braking Distance Calculator — run your exact scenario

Standard summer/all-season rubber compounds begin to harden below approximately 7°C. As rubber hardens, it can't conform to the road's micro-texture — and grip drops.

The science: Tyre rubber is a viscoelastic polymer. At operating temperature (20–60°C), it's pliable and moulds into the road surface's microscopic peaks and valleys. Below 7°C, the polymer chains stiffen and the tyre essentially becomes a harder plastic that slides over the same surface.

How much grip loss? A standard summer tyre at 0°C can lose 20–30% of its wet grip compared to the same tyre at 20°C. Winter compounds (with higher silica content) maintain flexibility down to -10°C or below.

NZ relevance:

• Central Plateau, inland Canterbury, and Otago regularly see sub-zero temperatures in winter

• Bay of Plenty and Northland rarely drop below 7°C — winter tyres aren't necessary

• If you commute over the Kaimai Range or Remutaka Hill in winter, consider tyres with 3PMSF (Three Peak Mountain Snowflake) rating

See our Terrain Types FAQ for details on 3PMSF-rated tyres.

Yes — but only 5–10 minutes of normal driving. No special warm-up routine needed.

Cold tyres (sitting overnight) are measurably less grippy than tyres at operating temperature. The rubber hasn't reached optimal flexibility and the internal air pressure is 2–4 PSI lower than when warm.

Practical impact:

• First 1–2 km: Grip is at its lowest. Drive calmly — avoid hard braking, sharp turns, or full throttle. This is when most cold-start accidents happen.

• 5–10 km / 10 minutes: Tyres reach normal operating temperature through flexing and road friction. Performance is at full capacity.

• Performance tyres: More sensitive to temperature. Soft-compound UHP tyres can feel "greasy" for the first 5 minutes in winter. Motorsport tyres need dedicated warm-up laps.

Pressure note: This is why tyre pressures should be checked "cold" (before driving or within the first 3 km). The placard pressure assumes cold tyres. Warm tyres read 2–4 PSI higher, which is normal and expected.

Water-based tyre dressings are fine. Solvent-based silicone "shines" can cause long-term damage.

The difference matters:

• Water-based dressings: Condition the rubber, restore natural colour, provide mild UV protection. Satin/matte finish. Safe for regular use. Brands like 303 Aerospace, Meguiar's Endurance are well-regarded.

• Solvent-based silicone sprays: Cheap, high-gloss "wet look." The solvents strip the protective anti-ozone waxes that manufacturers embed in the rubber compound. Short-term shine, long-term drying and cracking.

How to tell the difference: Solvent-based products feel slippery/oily and fling onto paintwork when driving. Water-based products absorb into the rubber and don't sling.

Best practice: Clean sidewalls with mild soap and water, rinse, dry, then apply a water-based protectant every 2–4 weeks. Skip the high-gloss look — it's literally dissolving your tyre's protective layer.

Solvent-based silicone sprays can accelerate sidewall cracking — and there's solid evidence for this.

The mechanism: Tyre manufacturers add anti-ozonant waxes and oils to rubber compounds. These migrate to the surface over time, forming a thin protective film (that's the natural brownish discolouration you see on sidewalls — it's supposed to be there). Solvent-based tyre shine products dissolve and strip this protective film.

Without the protective film:

• Ozone attacks the exposed rubber directly → surface cracking

• UV penetrates deeper → accelerated degradation

• Rubber dries out faster → brittleness and fracturing

NZ's high UV makes this worse. We have 40–50% more UV than equivalent Northern Hemisphere latitudes. A tyre that might last 6+ years in the UK can show cracking in 3–4 years in NZ — even faster if treated with solvent-based products.

See Rubber Compounds FAQ for more on ageing and storage.

NZ has some of the harshest UV conditions in the world for tyres. The ozone hole, clean atmosphere, and southern latitude combine to deliver UV levels 40–50% higher than equivalent northern latitudes.

Protection strategies:

• Park in shade when possible. A garage or carport is ideal. Even parking under trees or on the south side of a building reduces UV exposure significantly.

• Use water-based UV protectant. Products like 303 Aerospace Protectant or Meguiar's Endurance provide a UV-blocking layer. Apply every 2–4 weeks to sidewalls.

• Drive regularly. Tyres that sit for weeks lose their protective anti-ozonant bloom. Regular flexing during driving pushes fresh waxes to the surface.

• Avoid petroleum-based cleaners. Wheel cleaners containing strong solvents can damage rubber. Use pH-neutral or tyre-safe wheel cleaners.

• Tyre covers for stored vehicles. Caravans, boats, classic cars — any vehicle sitting for weeks needs UV covers on exposed tyres.

Expected lifespan in NZ: Well-maintained tyres 5–6 years. Neglected/exposed tyres 3–4 years regardless of tread remaining. Always check DOT date code — our DOT Code Decoder can read it for you.

Tyres on stationary vehicles develop flat spots, lose pressure, and age faster. Here's how to prevent damage:

If sitting 1–3 weeks:

• Inflate to 3–5 PSI above normal before parking. This compensates for natural air loss and reduces flat spot depth.

• Park on a clean, flat surface — avoid grass (moisture) or gravel (point loading).

• If possible, move the vehicle a few metres every week to change the contact patch position.

If sitting 1–3 months:

• Consider tyre cradles or ramps (foam or plastic ramps that distribute the load across a larger contact area)

• Over-inflate by 5–10 PSI. Check pressure every 2 weeks and top up.

• Ideally, drive the vehicle for 15–20 minutes every 2 weeks to warm the tyres and redistribute oils within the rubber.

If sitting 3+ months:

• Place the vehicle on jack stands to remove weight from the tyres entirely

• Cover sidewalls from UV exposure

See Rubber Compounds FAQ for detailed storage guidance.

Trailer and caravan tyres fail more often from age and storage damage than from wear. Most caravans in NZ cover only 3,000–8,000 km per year but sit in the sun for months.

Storage checklist:

• UV covers: Essential in NZ. Use opaque, breathable tyre covers — not black plastic bags that trap moisture.

• Inflate to maximum sidewall pressure during storage. This reduces flat spot formation and provides a buffer for natural air loss.

• Move the trailer monthly — even 1 metre forward or back changes the contact patch and prevents permanent flat spots.

• Check for cracking: Inspect sidewalls every 3 months for ozone cracking (small surface cracks that deepen over time).

• Block the wheels rather than relying on the handbrake — seized brake components are common on stored trailers.

Age limit: Replace caravan/trailer tyres at 5–6 years regardless of tread depth. A 7-year-old trailer tyre with full tread is more dangerous than a 2-year-old tyre at 3mm — the rubber has lost its flexibility and can fail suddenly at motorway speed.

🔍 DOT Code Decoder — check your caravan tyre age

Every 3 months — mark it in your calendar or check it every time the seasons change.

Spare tyres lose pressure just like your driving tyres — approximately 1–2 PSI per month through normal permeation. But because nobody checks them, spares are often found at 15–20 PSI when needed, or completely flat.

Correct spare tyre pressure:

• Full-size spare: Same pressure as your driving tyres (check door placard)

• Temporary/space-saver spare: 60 PSI (420 kPa). This higher pressure is essential because the tyre is smaller and must support the same vehicle weight on a smaller contact patch. The required pressure is stamped on the tyre.

NZ WOF note: The spare tyre is NOT inspected during WOF — but that doesn't mean it's safe to ignore. A flat spare when you need it is worse than no spare at all (because you've relied on having one instead of carrying a sealant kit).

🎯 PSI Calculator

Replace at 6–8 years maximum, regardless of tread depth or appearance. Spare tyres age faster than driving tyres because:

• They're often stored under the vehicle, exposed to road heat, water spray, and debris

• They don't get the regular flexing that drives protective anti-ozonant waxes to the surface

• Many NZ vehicles are imported with spares already several years old

How to check age: Find the DOT code on the sidewall — the last 4 digits indicate week and year of manufacture. "2519" = week 25 of 2019. If you can't find it or it's worn away, the tyre is too old.

Danger of old spares: A 10+ year old space-saver at 60 PSI can fail catastrophically. The rubber has lost flexibility, and the high pressure in an aged casing is a recipe for blowout — at exactly the worst time (you're already dealing with one tyre failure).

Alternative: If your spare is old and you don't want to buy a replacement, carry a modern tyre sealant kit and a 12V compressor instead. Lighter, cheaper, and works for most punctures.

🔍 DOT Code Decoder

Yes — as a temporary repair to get you to a tyre shop. Not as a permanent fix.

What a plug kit does: Inserts a sticky rope-like plug into the puncture hole from outside, without removing the tyre from the rim. The plug expands to seal the hole and is coated in rubber cement that vulcanises.

When it's appropriate:

• Tread-area puncture from a nail, screw, or wire (not sidewall)

• Hole is 6mm or smaller

• You're stranded and need to reach a tyre shop

Limitations:

• External-only repair — doesn't seal the inner liner

• No internal inspection for secondary damage

• Many tyre shops will refuse to do a proper repair over a plug — some insist on replacement

After plugging: Drive to a shop at reduced speed (under 80 km/h), get the tyre removed and inspected from inside, and have a proper mushroom plug-patch repair done if the tyre is repairable.

See Puncture Repairs FAQ for full repair standards.

Sealant kits: temporary, limited to 80 km/h. Mushroom plug repairs: fully safe at all speeds.

Sealant/inflator kits (the ones that come with new cars that have no spare):

• Rated for temporary use at up to 80 km/h

• Effective range: ~200 km maximum

• Only works on small tread punctures (under 4mm)

• The sealant is a temporary fix — you must get a proper repair or replacement within 200 km

Professional mushroom plug-patch repair:

• Full speed rated — no restrictions. The repair is permanent and as strong as the original tyre.

• Applied from inside the tyre after full inspection

• This is the NZ industry standard repair method

External rope plugs:

• Technically can hold at motorway speed

• Not recommended for sustained high-speed driving

• Should be replaced with a proper internal repair as soon as possible

Depends on where and how you drive. Here's our NZ-specific recommendation:

NZ reality: Many new vehicles come without spares (just a sealant kit). If you regularly drive SH3 Forgotten World Highway, Coromandel Peninsula, or Central Otago backcountry, a sealant kit alone is inadequate.

Roadside tyre changes are dangerous — 200+ people are killed per year in the US by passing traffic while changing tyres. In NZ, use these precautions:

Before jacking:

• Pull as far off the road as possible — ideally a flat, firm surface away from traffic

• Turn on hazard lights and place a warning triangle 50m+ behind your vehicle

• Apply handbrake firmly and put in gear (manual) or Park (auto)

• Place wheel chocks or large stones behind the diagonally opposite wheel

• All passengers out and well away from the vehicle and traffic

Jacking procedure:

• Use only the designated jacking points (check your owner's manual). Wrong placement can crush the sill or slip.

• Loosen wheel nuts/bolts 1/4 turn BEFORE lifting (while the tyre is still on the ground for resistance)

• Jack only high enough to clear the ground with the inflated replacement

• Never get under the vehicle with only a scissor jack supporting it

• Tighten nuts in a star pattern, hand-tight while raised, then full torque after lowering

If you're on a motorway shoulder: Seriously consider calling roadside assist instead. The 15 minutes you're kneeling beside the car is 15 minutes of risk from passing traffic at 100 km/h.

Stop and check pressures as soon as safely possible. The TPMS warning light means at least one tyre is 25% or more below recommended pressure — a significant safety concern.

What the light means:

• Solid light: Low pressure detected. Check all four tyres (plus spare if monitored) with a gauge. Inflate to placard pressure.

• Flashing light (then solid): System fault — a sensor has failed or lost communication. The system can't monitor pressure until repaired.

Is it OK to drive?

• If pressure is only 3–5 PSI low: Drive carefully to the nearest air source (petrol station). Inflate and the light should clear after a few km of driving.

• If one tyre is significantly low (10+ PSI below recommended): Do not drive at highway speed. Inflate or fit the spare.

• If you can't check: Drive slowly (under 50 km/h) to the nearest safe location to check.

NZ WOF note: TPMS is not a WOF requirement in NZ, but if your vehicle has it fitted, the system should be functional. A permanently illuminated TPMS light won't fail WOF by itself, but the underlying low pressure issue might.

See TPMS FAQ for sensor replacement, battery life, and reset procedures.

Five habits that will extend your tyre life by 20–40%:

1. Monthly pressure checks (saves 15–20% tread life): The single biggest factor. Under-inflation causes shoulder wear, over-inflation causes centre wear. 60 seconds at any petrol station. Use our PSI Calculator for your correct pressure.

2. Regular rotation (saves 10–15%): Every 8,000–10,000 km (5,000–6,000 for gravel drivers). Evens out the natural wear differences between driven and non-driven axles. Book a rotation — most shops do it in 20 minutes.

3. Annual alignment (saves 10–20%): A 2mm toe misalignment can scrub 1–2mm of tread in 5,000 km. $60–120 per year vs $600+ for premature replacement.

4. Smooth driving (saves 10–15%): Hard braking, aggressive cornering, and wheel spin accelerate wear dramatically. The difference between gentle and aggressive driving can be 20,000 km of tyre life.

5. Address suspension issues promptly: Worn shocks, bushings, or ball joints create uneven wear patterns that can't be fixed by alignment alone. Fix the cause before fitting new tyres.

Combined effect: A driver who follows all five habits might get 65,000–75,000 km from a set of Anchee AC808s. A driver who ignores them might get 35,000–40,000 km from the same tyres.

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