Unlike load ratings (which must match exactly), speed ratings don't need to be identical on an axle — they just both need to meet or exceed your vehicle's specification.

Example:

• Vehicle requires: H (210 km/h)
• 205/55R16 91H + 205/55R16 91V on same axle = ✓ WOF OK
• Both meet H requirement, V just exceeds it

Load indexes don't need to be identical on the same axle, but they must be close. The accepted tolerance is within 2 index points.

Examples:

• Front right: load index 91 → Front left can be 89 to 93 = ✓ WOF OK
• 205/55R16 91V + 205/55R16 92V = ✓ Fine (1 point difference)
• 205/55R16 91V + 205/55R16 95V = ❌ Likely fail (4 points apart)

Why close matching still matters:

• Even 2 points represents a difference in sidewall stiffness
• Large gaps create uneven handling — one side flexes more than the other
• Under hard braking or cornering, response becomes less predictable
• Traction control can be confused by different grip characteristics

🔧 WOF Tyre Guide | 📖 Load Rating Guide

This is more nuanced than most people realise. Your door placard specifies one or more tyre sizes, each with its own load index. The load rating you need depends on which size you're fitting.

Example — Nissan X-Trail (2008):

• Placard option 1: 215/65R16 98H
• Placard option 2: 215/60R17 96H

If you're fitting the R16 size, you need load index 98+. If you're fitting the R17 size, you only need 96+. The required load index changes because different sized tyres carry weight differently.

What about changing to a size not on the placard?

If you're switching to a size within the ±5% diameter rule that isn't listed on your placard, the general principle is: your tyres must support the vehicle's gross axle weight. In practice, staying at or above the load index of your placard's closest equivalent size is the safest approach.

📖 Load Rating Guide | Not sure? Send us your placard photo

For WOF compliance, tyres on the same axle must match in:

• Width (e.g., 205mm)
• Aspect ratio (e.g., /55)
• Rim diameter (e.g., R16)
• Construction type (Radial vs bias-ply)

Example: 205/55R16 + 215/55R16 on same axle = ❌ Fail WOF

In New Zealand, without LVV (Low Volume Vehicle) certification:

Example calculation:

• Original: 205/55R16 = 632mm diameter
• 5% of 632mm = 31.6mm
• Allowed range: 600mm – 664mm diameter without certification

Additional requirements even within 5%:

• No rubbing on suspension, guards, or bodywork at full lock or over bumps
• Load capacity must meet or exceed original specification
• Speed rating must meet or exceed original specification
• Speedometer must remain reasonably accurate

🔧 Tyre Size Calculator — shows exact percentage difference and WOF compliance status

Width changes affect multiple factors:

• Grip: Wider = more contact patch = potentially more grip
• Fuel economy: Wider = more rolling resistance = slightly worse
• Clearance: May rub on suspension or guards
• Rim width: Your rim must support the wider tyre (check rim width range)

Common upgrade example:

• Original: 195/65R15 (635mm diameter)
• Wider option: 205/60R15 (619mm diameter) — within 5%, typically fits

Considerations:

• Check your rim width — a 6" rim suits 185-205mm, a 7" suits 195-225mm
• Test at full steering lock and over bumps for rubbing
• Consider wheel offset if fitting much wider tyres

🔧 Tyre Size Calculator — includes rim width compatibility

How tread is measured:

• Measured in the main grooves, not the sipes (small cuts)
• Must meet 1.5mm across the central 75% of tread width
• The outer 12.5% on each edge doesn't count for the 75% rule
• Must meet minimum around the entire tyre, not just one spot

Why 3mm matters:

• Wet braking: Stopping distances increase dramatically below 3mm — up to 50% longer in wet conditions
• Aquaplaning: Risk increases significantly as tread wears
• NZ conditions: Our wet winters make adequate tread critical

Tread depth by tyre type (new):

• Passenger: 7-8mm | Highway Terrain: 9-10mm
• All Terrain: 11-13mm | Mud Terrain: 15-18mm

🔧 WOF Tyre Guide | 🔧 Braking Distance Calculator

WOF doesn't specify a maximum tread difference, but significant variation causes problems:

Effects of uneven tread on same axle:

• Vehicle pull: Car pulls toward the side with less tread
• Handling: Uneven grip left-to-right, especially in wet
• Tyre life: Can reduce remaining life significantly

Recommendations:

• <2mm difference: Acceptable, monitor wear
• 2-3mm difference: Consider rotation to balance wear
• >3mm difference: Replace the lower tread tyre or swap positions

• Tread depth: Below 1.5mm on 75%+ of tread width
• Exposed cords: Visible steel or fabric cords anywhere
• Sidewall bulges: Lumps or bubbles indicating internal damage
• Cuts exposing cords: Deep cuts penetrating reinforcing layers
• Severe cracking: Cracking that reaches cords or compromises structure
• Bead damage: Damage to bead area or improper seating
• Run-flat damage: Evidence of driving on a flat
• Sidewall repairs: Any repair in the sidewall area
• Tread separation: Tread peeling from the carcass

• Surface cracking from age (depends on severity)
• Minor cuts not reaching cords
• Uneven wear patterns
• Repaired tyres (acceptable if done correctly in tread area)

🔧 WOF Tyre Guide — full visual inspection checklist

Why this is dangerous: Radials flex in the sidewall while bias-ply flex across the entire tyre. Mixing creates completely unpredictable handling, especially in emergency manoeuvres.

How to identify construction type:

• R in size = Radial (e.g., 205/55R16) — standard modern construction
• - hyphen in size = Bias-ply (e.g., 7.50-16) — older construction

There are two things people mean by "different patterns" — and the rules are different for each:

You can have a Predator Comptrax next to an Anchee AC818 on the same axle, as long as they're the same size, within ±2 load index, both meet speed rating, and crucially — they're the same pattern type Symmetrical.

There are three pattern types, and both tyres on an axle must be the same type:

• Symmetric: Same pattern left-to-right, no directional markings
• Directional: V-shaped pattern with arrow/rotation marking — must point forward
• Asymmetric: Different inner/outer design with "OUTSIDE" marking

If front right is symmetric, front left must also be symmetric. You can't mix a directional with an asymmetric on the same axle — the grip characteristics are too different.

📖 Tread Pattern Guide — Directional vs Asymmetric vs Symmetric

As long as both tyres match in size, are within ±2 load index points, both meet minimum speed rating, and are the same pattern type (symmetric/directional/asymmetric) — you can absolutely run different brands side by side.

This is actually how most people upgrade their tyres. Very few drivers replace all four at once. If one tyre needs replacing, you buy a pair and fit them to the same axle — and that new pair doesn't need to be the same brand as what's on the other axle.

Where this works in your favour:

• You don't have to keep buying the same expensive brand just because your car came with it
• When replacing a pair, you can switch to a brand that offers better value without changing all four
• Premium-quality tyres from brands like Predator and Anchee are designed to be fully compatible with — and often outperform — the brands they replace

Real-world example: Your car has Blacklion tyres and two need replacing. A pair of Anchee AC808s in the same size will match or exceed the performance at a similar or better price point. Fit them on one axle and you're good to go.

Not sure which of our brands matches your current tyres? Get a quote →

AT and MT tyres have different pattern types, vastly different tread depths, and completely different grip characteristics. On the same axle, one side will grip significantly more than the other — especially in wet — creating dangerous handling imbalance.

Having MT on the rear and AT on the front (or vice versa) isn't specifically prohibited in NZ WOF rules — each axle matches internally. However:

• Handling: Front and rear grip levels are dramatically different, making the vehicle unpredictable
• 4WD/AWD systems: Traction control gets confused by different traction levels per axle
• Braking: Uneven front/rear grip creates inconsistent braking behaviour
• Off-road: The AT axle becomes the weak link — you only go as far as your least capable tyres

The right approach: Fit matching tyres on all four corners and choose the terrain type for your primary use case. 80% road + 20% off-road → AT. 50%+ serious off-road → MT. Want both? → RT (Rugged Terrain).

📖 4WD Tyre Guide — Choose Your Terrain Type

HT and AT tyres have different tread patterns, different rubber compounds, different noise levels, and different grip characteristics. Tread depth also varies significantly between them — though exact depths depend on the brand, model, and tyre size (a 315/75R16 AT will have much deeper tread than a 205/70R15 AT).

Same axle: Likely WOF failure — different pattern types with different grip levels left-to-right.

Different axles: Not illegal but handling will be compromised — especially noticeable in wet and when braking.

This is a common misconception. The rims on BMW, Mercedes, and other vehicles that come with run-flat tyres are standard rims — they'll accept normal tyres without any issue. The run-flat technology is in the tyre (reinforced sidewalls), not in the rim.

You can replace all four run-flats with standard tyres. Many owners do this for:

• Better ride comfort: Standard tyres have softer sidewalls
• More choice: Far wider range of brands and models available
• Lower cost: Standard tyres are significantly cheaper than run-flat equivalents

It's all four run-flat OR all four standard. Mixing creates dangerous handling imbalance due to vastly different sidewall stiffness. Not on the same axle, not on different axles — don't mix them at all.

If you switch to standard tyres, be aware:

• No spare: Most run-flat vehicles have no spare tyre — if you go flat, you're stranded
• Carry a backup: Repair kit + portable inflator at minimum, or add a space-saver spare if storage allows
• TPMS is critical: Without run-flats, you're entirely dependent on TPMS to warn you of pressure loss — make sure it's working

Run-flat tyres have reinforced sidewalls that are significantly stiffer than standard tyres. Mixing them creates:

• Unequal sidewall flex: One tyre deforms more than the other under cornering loads
• Different grip profiles: The stiffer run-flat responds differently to steering inputs
• Handling imbalance: Vehicle pulls or behaves unpredictably, especially in emergency manoeuvres
• Different deflation behaviour: If both go flat, one can still drive, the other can't

XL and SL (Standard Load) are construction categories, not load ratings themselves. What matters for WOF is the actual load index number:

• A 205/55R16 91V (SL) and a 205/55R16 94V XL have different load indexes (91 vs 94) = ❌ Fail WOF
• However, if you found an SL 94 and an XL 94 in the same size (rare), the load indexes match = technically OK

Why mixing is still not ideal:

• XL tyres have stiffer sidewalls and require higher pressure to achieve their rated load
• Different ride characteristics and flex behaviour on the same axle
• Different optimal pressure settings left-to-right

Full-time AWD systems (Subaru Symmetrical AWD, most modern SUVs) constantly drive all four wheels through a centre differential. If tyres have different rolling circumferences, the system works overtime trying to compensate:

• Centre differential stress: Constant torque imbalance causes premature wear
• Transfer case damage: On viscous coupling systems, mismatched circumferences generate excessive heat
• CVT damage: Subarus with CVT are especially sensitive — repair costs $5,000-$10,000+

Part-time 4WD (e.g., Toyota Hilux with part-time 4WD) is less critical in 2WD mode, but matching is still important when 4WD is engaged.

This depends on your specific AWD system, but general guidelines:

• Subaru (Symmetrical AWD): Maximum 2/32" (~1.6mm) difference across all four
• Most other AWD systems: Maximum 3-4mm difference is generally safe
• Part-time 4WD: Less critical in 2WD, but match as closely as possible

Real-world example: Your Subaru Outback has three tyres at 5mm and one at 2mm after a puncture replacement. That 3mm difference exceeds Subaru's tolerance and could damage the centre differential over time. Options: replace all four, or have the new tyre "shaved" to match existing depth.

Mismatched rolling circumferences force the AWD system to constantly correct. Over time, this causes:

• Centre differential wear: Clutch packs or viscous couplings overheat and fail
• Transfer case failure: Bearings and gears wear prematurely
• CVT damage: On Subaru and Nissan CVTs, belt/chain stress from torque imbalance
• Prop shaft vibration: Uneven rotation causes driveline vibrations

Repair costs in NZ:

• Centre differential rebuild: $2,000-$4,000
• Transfer case replacement: $3,000-$6,000
• CVT replacement (Subaru): $5,000-$10,000+
• Four new tyres: $400-$1,200

On AWD, fitting two new tyres (7-8mm tread) with two worn rears (3-4mm) creates a 3-4mm circumference difference — this can stress the drivetrain.

When it's OK:

• Rear tyres are 5mm+ tread (minimal difference to new)
• You're driving a part-time 4WD mostly in 2WD mode
• You plan to replace the rears within a few months

When you should replace all 4:

• Full-time AWD (Subaru, most modern SUVs)
• Rear tread is below 4mm
• More than 3mm difference between new and existing

Ideally yes for full-time AWD. Not always for part-time 4WD.

Full-time AWD (Subaru, RAV4 AWD, CX-5 AWD, Outlander, X-Trail):

• Replace all four if existing tyres are below 50% tread
• If only one tyre is damaged and the others are nearly new, you can sometimes have the new tyre "shaved" to match existing tread depth
• Always check your owner's manual for specific manufacturer tolerance

Part-time 4WD (Hilux, Ranger, Navara in 2WD mode):

• Pairs are usually fine (same axle)
• When engaging 4WD, matching all four is better but occasional short-term use is OK

A space saver spare has a much smaller diameter than your full-size tyres, creating an immediate circumference mismatch. On AWD systems:

• Maximum 80 km/h — this is printed on the spare for good reason
• Maximum distance: Get to the nearest tyre shop — don't drive across the country on it
• Some AWD systems: Automatically disengage AWD when a space saver is detected (via wheel speed sensors)
• Others don't: And the centre diff takes the punishment

Best practice for AWD owners:

• Carry a full-size spare matching your current tyres if space allows
• If using a space saver, minimise distance — drive directly to a tyre shop
• Consider a tyre repair kit + inflator as an alternative for minor punctures

Many vehicles specify different front and rear pressures on the door placard (e.g., 32 PSI front, 30 PSI rear). This is fine — the AWD system compensates easily for the minor rolling circumference change from pressure differences.

What DOES cause problems:

• One tyre significantly under-inflated: A slow puncture causing one tyre to run at 15 PSI while others are at 32 PSI changes circumference enough to stress the system
• Left-to-right imbalance on same axle: One tyre at 32 PSI and the other at 22 PSI creates handling problems and confuses traction control

Key rule: Both tyres on each axle should always be the same pressure. Front-to-rear can differ per manufacturer spec.

🔧 PSI Calculator — get correct pressures for your vehicle and load

It depends on your drivetrain:

• Many AWD systems require matched tyre circumference (see AWD section above)
• Can damage transfer cases, centre differentials, and CVTs
• Some manufacturers specify maximum 2-3mm tread difference across all 4

• Replace in pairs on the same axle
• Put newer tyres on the rear axle for stability
• Single tyre replacement only if existing tyre is nearly new

This is one of the most debated topics in the tyre world. The industry standard recommendation is rear — but there are genuine arguments for both. Here's the full picture:

🔙 New tyres on the REAR — the safety-first approach:

• Prevents oversteer: Better rear grip stops the back end sliding out (fishtailing) in wet conditions
• Oversteer is harder to recover: If the rear slides, the car spins — most drivers can't correct this
• Understeer is safer: If the front slides, you naturally slow down and the car straightens
• Industry consensus: All major tyre manufacturers and safety organisations recommend this

Downside: Your front tyres (which do most of the braking and all of the steering) stay on the older, less grippy rubber.

🔜 New tyres on the FRONT — the practical approach:

• Better braking: Front tyres do 60-70% of braking work — newer rubber means shorter stopping distances
• Better steering response: More grip where you steer = more precise handling
• Better traction (FWD): Front-wheel drive cars accelerate through the front tyres
• Slower wear: New tyres on the less-worked rear axle last longer — some drivers prefer the maths

Downside: Reduced rear grip in wet corners — risk of the back end stepping out.

When single replacement is acceptable:

• Existing tyres have 80%+ tread remaining (nearly new)
• You can find an exact match: same brand, model, size
• Tread difference will be less than 2-3mm
• 2WD vehicle (not full-time AWD)

When you should replace in pairs:

• Existing tyres are at 50% tread or less
• Can't find exact matching tyre
• AWD vehicle with strict circumference requirements

Staggered fitment means the rear tyres are wider and/or larger diameter than the fronts — this is a factory specification on some vehicles.

Common on: BMW M series, Porsche, Corvette, Mustang GT, Mercedes AMG, some SUVs with performance packages.

Why manufacturers do this:

• Rear traction: Wider rear tyres = more rubber for acceleration (especially RWD)
• Handling balance: Induces slight understeer for safety
• Weight distribution: Larger rears on heavier rear-biased vehicles

Potential issues: Vehicle was engineered for specific front/rear grip balance. Front wheel wells may not accommodate wider rears. Traction control calibrated for specific setup.

You can potentially fit the front size on all 4 corners (smaller, fits everywhere). This may dull handling but is usually safe. Check overall diameter stays within 5%.

Allowed rotation: Front left ↔ Rear left. Front right ↔ Rear right.

NOT allowed (without remounting): Side-to-side or cross-rotation. If cross-rotation is needed, tyres must be removed from rims and remounted so the arrow points correctly — adds cost.

📖 Tread Pattern Guide

Just keep "OUTSIDE" facing outward. As long as that's correct, you can do front-to-back, side-to-side, or cross rotation. This makes asymmetric tyres more flexible for rotation than directional tyres.

📖 Tread Pattern Guide

Yes. Changing overall diameter directly affects speedometer and odometer accuracy:

• Larger diameter: Speedo reads LOWER than actual speed (dangerous — you're going faster than you think)
• Smaller diameter: Speedo reads HIGHER than actual speed (annoying but safe)

Example:

• Original: 205/55R16 (632mm) → New: 215/60R16 (665mm) — 5.2% larger
• When speedo shows 100 km/h, you're actually doing 105 km/h

🔧 Tyre Size Calculator — shows exact speedometer impact for any size change

Modern vehicles use wheel speed sensors to control ABS, ESC (Electronic Stability Control), and traction control. These systems are calibrated for the factory tyre size. Changing size affects:

• ABS: Calculates wheel lock-up based on expected rotation speed. Significantly different sizes may cause earlier or later ABS activation
• ESC/VSC: Detects loss of control by comparing wheel speeds. Different sizes can trigger false activations or delayed response
• Traction control: Monitors wheel spin against expected speed — mismatched sizes may confuse the system

How much change causes problems?

• Within 3%: Most systems compensate without noticeable effect
• 3-5%: Some sensitivity changes, usually still functional
• Over 5%: Recalibration may be needed — consult your dealer

Three methods, from easiest to most precise:

1. GPS speed comparison (easiest):

• Use Google Maps, Waze, or a dedicated GPS speedometer app
• Drive at a steady indicated 100 km/h on a flat highway
• Compare your speedo reading to GPS speed
• GPS is accurate to ±1 km/h — much more reliable than your speedo

2. Tyre Size Calculator (most convenient):

• Enter your original and new tyre sizes into our calculator
• It shows exact speedo error percentage at every speed

3. Measured distance test:

• Reset trip odometer at a known distance marker (motorway posts are 1km apart)
• Drive exactly 10km by road markers
• Compare to odometer reading — the difference is your error

🔧 Tyre Size Calculator

Without LVV certification:

• Small spacers (typically 5-15mm) that don't change track width significantly — generally OK
• The combined tyre + spacer must not cause tyres to protrude past guards
• Must not cause rubbing at full lock or over bumps
• Wheel studs must still have adequate engagement (minimum 1× stud diameter)

LVV certification required when:

• Track width increases by more than 25mm per side from original specification
• Stud pattern adapters (e.g., 5×100 to 5×114.3) — always require certification
• Spacers causing tyres to protrude past guards

Aftermarket wheels are fine for WOF without LVV if:

• Correct PCD (bolt pattern) for your vehicle
• Adequate load rating for the vehicle's gross axle weight
• Correct centre bore (or properly hub-centric with rings)
• Appropriate offset — tyres don't protrude past guards or rub on suspension
• Overall tyre diameter stays within ±5% of original
• Recognised safety marking: JWL (Japan), VIA (Japan), TÜV (Germany), SAE (USA), or AS 1192 (Australia)

LVV certification IS required if:

• Track width increases beyond 25mm per side
• Combined with other modifications (lift kit, suspension changes)
• No recognisable safety certification on the wheels

LVVTA (Low Volume Vehicle Technical Association) guidelines state:

How track width changes:

• Different offset wheels: Lower ET number = wheel sits further out
• Wider wheels: May push tyre outer edge further out
• Wheel spacers: Directly increase track width
• Wider tyres: On same wheel, minimal track change; on wider wheel, more significant

Measuring track width: Measured from tyre centre to tyre centre across the axle. Compare to factory specification to determine your change.

Without LVV certification (generally OK):

• Suspension lift up to 50mm (2 inches) on most vehicles
• Tyre diameter within ±5% of original
• No rubbing, no protrusion past guards
• Headlight aim corrected

LVV certification required:

• Suspension lift over 50mm
• Body lift over 50mm (or any body lift combined with suspension lift exceeding 50mm total)
• Tyre diameter change over 5%
• Combined modifications that affect vehicle dynamics significantly

Common NZ 4WD scenario: 2" lift + 33" tyres on a Hilux/Ranger. The lift alone is within tolerance, but 33" tyres on a vehicle that came with 30" may exceed the 5% diameter rule — check with our calculator.

Without LVV:

• Lowering up to 50mm with quality lowering springs — generally OK
• Low-profile tyres within the 5% diameter rule — fine
• No rubbing at full lock, over bumps, or with passengers

LVV required:

• Lowering over 50mm from factory ride height
• Coilover systems that allow adjustment beyond 50mm
• Combined with wide wheels, stretched tyres, or significant offset changes
• Static/bagged setups that sit below legal minimum ride height

WOF considerations:

• Minimum ride height rules apply — no contact with road surface over normal bumps
• Adequate suspension travel must remain
• Headlight aim must be corrected

Quick reference summary:

• Aftermarket wheels with correct PCD, load rating, and safety markings
• Tyre size within ±5% overall diameter
• Track width increase up to 25mm per side
• Small spacers (not changing track width significantly)
• Lowering or lifting up to 50mm
• Low-profile or plus-size tyres within diameter tolerance

• Tyre diameter change over ±5%
• Track width increase over 25mm per side
• Suspension lift or drop over 50mm
• PCD adapters (changing bolt pattern)
• Combined modifications exceeding individual thresholds
• Wheels without recognised safety certifications

"Tyre stretch" means fitting a tyre on a rim wider than the manufacturer's recommended range. Common in the stance/hellaflush scene.

WOF inspector considerations:

• Bead seating: If the tyre bead isn't fully seated on the rim, it can de-bead under load — automatic fail
• Sidewall exposure: If the sidewall is pulled outward exposing the inner liner, that's structural compromise
• Rim lip contact: The rim edge can cut into the sidewall under load

Manufacturer rim width range: Every tyre has a specified rim width range (e.g., 7-8.5 inches for a 225). Going beyond this range voids the tyre manufacturer's warranty and puts you in WOF risk territory.

Inspectors check for evidence of rubbing during:

• Full steering lock: Turn wheels fully left and right
• Suspension compression: Push down on each corner to simulate bumps
• Visual evidence: Wear marks on inner guards, tyre sidewall scuffing, or missing guard liner

Common causes:

• Tyres too wide for the wheel wells
• Wheel offset too low (wheels sitting too far out)
• Lowered suspension reducing clearance
• Missing or damaged guard liners

Fixes: Correct wheel offset, narrower tyres, guard rolling/flaring (may require LVV), or adjusting suspension back to safe clearance.

This is checked by viewing the vehicle from directly above each wheel arch. If any part of the tyre's tread face is visible beyond the guard edge, it's a WOF failure.

Why this rule exists:

• Exposed tread throws debris (stones, water) at following vehicles
• Increased spray risk in wet conditions
• Pedestrian safety — exposed tyre edge is a hazard

Solutions if tyres protrude:

• Wheels with higher offset (ET) to tuck tyres inward
• Narrower tyres
• Guard flares — but these may require LVV certification if they change the vehicle's body dimensions
• Remove spacers if fitted

There's no NZ law against aggressive tread patterns on public roads. However, MT tyres must still meet:

• Minimum 1.5mm tread depth (measured in the main grooves between lugs)
• Correct size, load rating, and speed rating for the vehicle
• No damage or defects
• All standard WOF tyre requirements

"NHS" (Not for Highway Service) means the tyre is designed for off-road or specialist use only. These tyres:

• May not have adequate speed ratings for road use
• May not meet road-going construction standards
• Are typically found on ATV tyres, agricultural equipment, golf carts, and some extreme off-road tyres
• Don't carry the required E-mark (ECE approval) for road use

Will pass WOF:

• Road-legal semi-slicks (e.g., Toyo R888R, Nankang AR-1) — they have tread depth, speed/load ratings, and E-mark approval
• Track-focused tyres that still meet minimum 1.5mm tread depth requirement

Will NOT pass WOF:

• Full slick tyres (no tread pattern at all)
• Tyres marked "competition use only" or "not for highway use"
• Tyres without E-mark or adequate speed/load markings
• Worn semi-slicks below 1.5mm (they have very shallow tread to start with — they reach the limit quickly)

Space saver and temporary spares have:

• Maximum 80 km/h speed limit — printed on the tyre
• Reduced load capacity: Not designed for sustained driving
• Minimal tread depth: Limited wet weather grip
• Different diameter: Causes ABS/ESC/AWD system confusion
• Higher pressure requirement: Typically 60 PSI — must maintain this or it'll fail faster

Risks of extended use:

• Accelerated wear on the differential (especially AWD)
• Uneven brake wear
• Compromised emergency handling
• Potential WOF failure if inspector identifies it as non-standard

NZ WOF doesn't have a specific age limit, but tyres are inspected for age-related degradation:

• 0-5 years: Generally fine if stored/used correctly
• 6+ years: Requires careful inspection for cracking, hardening
• 10 years: Industry recommendation to replace regardless of tread depth

Check tyre age: DOT code on sidewall — last 4 digits show week and year. e.g., "2521" = week 25 of 2021.

🔧 DOT Code Calculator — decode manufacture date and factory

• Puncture in the tread area only (central 75%)
• Puncture diameter ≤6mm
• Professional plug-patch repair (combination repair from inside)
• No sidewall involvement, no run-flat damage

• Sidewall damage or puncture
• Shoulder area puncture (within 20% of edge)
• Over 6mm diameter puncture
• Evidence of driving flat (internal damage)
• Bead area damage
• Multiple repairs too close together

WOF inspects that the valve stem is present and functional, but a missing cap alone won't fail you. However:

• Dirt and moisture: Without the cap, debris enters the valve core causing slow leaks
• Corrosion: Valve cores corrode faster without protection, especially in coastal NZ areas
• Slow leaks: A corroded or dirty valve core is one of the most common causes of gradual pressure loss

Valve caps cost about $2-$5 for a set of four. Replace them.

A bead leak is air escaping between the tyre bead and the rim. If the tyre is visibly under-inflated at inspection, it may be flagged. Common causes:

• Rim corrosion: Alloy or steel wheels corrode where the bead seats, creating gaps
• Impact damage: Pothole hits can unseat the bead slightly
• Old bead sealant: Previous sealant has dried and cracked

Fix: Remove tyre, clean rim corrosion, apply fresh bead sealant, reseat and inflate. Most tyre shops do this during fitting. Cost: $20-$40 per tyre if done separately.

Light kerb rash or surface abrasion that hasn't penetrated the outer rubber layer is typically not a WOF failure. The inspector assesses:

• Depth: Has the scuff penetrated to the cords/reinforcing? If yes → fail
• Size: Small surface mark vs large gouged area
• Location: Sidewall damage is always taken more seriously than tread area marks
• Structural compromise: Any bulging, deformation, or flex around the mark

The 1.5mm rule applies across 75% of the tread width, around the entire circumference. So if one edge is worn to 1mm while the centre is 5mm, the tyre fails.

Common uneven wear patterns:

• Inner edge wear: Usually alignment — too much negative camber or toe-out
• Outer edge wear: Hard cornering, positive camber, or toe-in
• Centre wear: Over-inflation
• Both-edge wear: Under-inflation

Inspector may also note: Severe uneven wear indicates an underlying mechanical issue (alignment, suspension). They may advise getting it checked even if tread is still legal.

Cupping (scalloping) creates dips and high spots around the tread. The WOF measurement takes the shallowest point. If the dips are below 1.5mm, the tyre fails — even if the high spots are 4mm+.

What causes cupping:

• Worn shock absorbers: The most common cause — tyre bounces rather than maintaining consistent contact
• Worn suspension bushes: Allow the wheel to wobble slightly
• Imbalanced tyres: Vibration causes irregular wear patterns
• Infrequent rotation: Front tyres on FWD vehicles cup if not rotated

Fix the cause: Replacing tyres without fixing worn shocks means the new tyres will cup too. Replace shocks first, then tyres.

The shoulder is the transition zone between tread and sidewall. Repairs in this area are unreliable because:

• Flex zone: The shoulder flexes significantly during cornering — repairs can't withstand this movement
• Heat buildup: Shoulders generate more heat than the tread centre
• Structural integrity: The reinforcing plies change direction here — patches don't bond reliably

The repairable zone: Only the central tread area (inner 75% of tread width) can be safely repaired. Everything outside that = replace the tyre.

There's no NZ law specifying a maximum number, but industry guidelines recommend:

• Maximum 2 repairs in the tread area for passenger tyres
• Maximum 3 repairs for LT/commercial tyres (larger repair area)
• Repairs must be at least 400mm apart (measured along the inner liner)
• No repair should overlap another

Our recommendation: After 2 repairs, the cost of another repair approaches the value of a new budget tyre. Consider replacing rather than accumulating patches.

The repairable zone is the central 75% of the tread width. If the nail entered closer to the sidewall:

• Outer 12.5% on each side: Too close to the shoulder flex zone — replacement recommended
• On the shoulder itself: Absolutely not repairable
• In the sidewall: Never repairable — immediate replacement

Tyre sealant (liquid products injected through the valve) is designed as a temporary get-you-home solution:

• WOF: A tyre holding pressure and meeting all other requirements will pass, regardless of what's inside it. The inspector can't see sealant.
• However: Sealant can mask damage that should be professionally assessed
• Permanent repair: Most tyre shops strongly prefer to remove sealant and do a proper plug-patch repair. Sealant can make proper repair more difficult.

Practical advice:

• Use sealant to get to a tyre shop — not as a permanent fix
• Tell the fitter you've used sealant (they need to clean the inside before patching)
• Some sealants corrode TPMS sensors — check compatibility

Changing wheel or tyre size from factory specification counts as a modification in most insurance policies. This includes:

• Different rim diameter or width
• Significantly different tyre size
• Wheel spacers
• Plus-sizing (larger rims with lower profile tyres)
• Lift kits that change tyre clearance or size

What happens if you don't declare:

• At claim time, the assessor inspects the vehicle
• Undeclared modifications can result in reduced payout or claim decline
• The insurer may argue the modification contributed to the accident
• Policy may be voided entirely for non-disclosure

If you're in an accident and the insurer's assessor finds:

• Tyres outside the 5% diameter tolerance without LVV certification
• Speed rating below vehicle specification
• Load rating below vehicle specification
• Mismatched tyres on the same axle
• Stretched tyres outside manufacturer spec
• Tread below legal minimum

The insurer can argue the non-compliant tyres contributed to loss of control, increased braking distance, or failure to maintain the vehicle to legal standard.

Keep these documents accessible:

• Purchase receipts: Show brand, model, size, date — proves what was fitted
• Fitting records: From the tyre shop showing correct installation
• LVV certification plate: If modifications require it — permanently attached to vehicle
• Wheel specifications: Load rating, PCD, offset, safety certifications (JWL/VIA/TÜV)
• WOF history: Passing WOF with modified setup demonstrates compliance at time of inspection
• Door placard: Shows factory specifications for comparison

Tyre chains are legal and sometimes mandatory on certain NZ alpine roads:

• Milford Road: Chains may be required October-April during snow events
• Crown Range: Chain advisory signs are used
• Ski field access roads: Many require chains or 4WD during snow
• Arthur's Pass, Lewis Pass: Chain advisory areas

Rules for chain use:

• Fit to drive wheels (front on FWD, rear on RWD, all four on 4WD recommended)
• Maximum 50 km/h with chains fitted
• Remove chains as soon as road is clear of snow/ice — chains on dry road damage the surface and your tyres
• Must be correct size for your tyres — check chain sizing guide

Textile snow socks (like AutoSock or ISSE) slip over the tyre and provide grip on snow and ice. They're:

• Accepted by NZ police as a chain alternative on most roads
• Easier to fit than traditional chains (no jack required)
• Less damaging to the road surface
• Lighter and easier to store
• Suitable for vehicles where chains don't fit (low clearance)

Unlike some countries (Scandinavia, parts of Canada), NZ does not permit metal-studded tyres on public roads because:

• NZ's road surfaces are primarily chipseal — studs cause significant damage
• NZ rarely has sustained ice conditions that justify studs
• Chains and snow socks provide sufficient traction for NZ winter conditions

Alternatives for NZ winter driving:

• All-season tyres: Good for cold mornings and light frost
• Winter/snow tyres: Softer compound for better grip below 7°C
• Chains or snow socks: For snow and ice on alpine roads
• Good AT tyres: Reasonable cold-weather performance with all-road capability

Second-hand tyres must meet the same WOF requirements as new: minimum tread, no damage, correct size/ratings, matching on axle.

Hidden risks: Unknown history (may have been run flat or overloaded), age disguised as "low km," internal damage not visible without dismounting, poor previous repairs, uneven wear indicating prior issues.

Our recommendation: New budget tyres often cost similar to quality used — and come with warranty and known history. Browse our budget options.

Valve stems: Must be present, functional, and not leaking. Damaged or leaking valves will fail.

If your car came with TPMS, it doesn't need to be functional for WOF. However, keeping it working is strongly recommended — it's your early warning for pressure loss.

Fails WOF: Cracked rims, significant bends, severe corrosion affecting bead seal, weld repairs (depends on quality), missing/damaged wheel studs, incorrect wheels for vehicle.

Usually OK: Kerb rash/scuffs, minor scratches, surface corrosion not affecting function.

Inspectors don't routinely check pressure against your door placard. But they DO check uneven wear (caused by wrong pressure), sidewall damage from under-inflation, and overall tyre condition. Incorrect pressure causes accelerated uneven wear — which CAN fail WOF.

🔧 PSI Calculator — get correct pressure for your tyres and load

Benefits are marginal for most drivers — air is already 78% nitrogen. More stable pressure, slower leakage, no moisture. You can top up with regular air if needed (mixing is fine). WOF doesn't care what gas is inside your tyres.

Not necessarily across all four — but each axle must match internally.

🔧 WOF Tyre Guide — full compatibility checker

DIY WOF pre-check:

1. Tread depth (20c coin test): Insert coin into main grooves, Queen's head down. If you can see the top of the head → below 3mm (replace soon).

2. Visual inspection: Check for bulges, cuts, cracks, exposed cords, uneven wear on all four tyres including sidewalls.

3. Age check (DOT code): Last 4 digits = week and year. 6+ years = inspect carefully. 10+ = replace.

4. Axle matching: Compare both tyres on each axle — same size? Same load rating? Same pattern type?

🔧 WOF Tyre Guide — interactive pass/fail assessment

Similar standards, some differences:

• Tread depth: Both NZ and AU = 1.5mm minimum
• Size tolerance: NZ = ±5% diameter. AU varies by state — typically similar or stricter
• Frequency: NZ = annual for 3+ years. AU varies by state — some only at sale/registration

Both check the same fundamentals — tread, damage, matching, ratings. Our WOF Guide also includes Australian Roadworthy standards for comparison.

Five places to check:

• Door placard (most reliable) — sticker inside driver's door frame with size, pressure, and ratings
• Owner's manual — usually in "Tyres" or "Specifications" section
• Fuel filler flap — some vehicles (especially European) display info here
• Current tyre sidewall — but previous owner may have changed sizes, cross-reference with placard
• Our fitment database — 84,000+ NZ vehicle fitments with OE sizes (see our Tyre Sizes FAQ for important limitations on rego lookups)