🔍 Tyre Age Calculator & DOT Code Decoder
Enter just 4 digits for instant age results, or decode the full DOT code to find manufacturer and origin. The only NZ tool with 1,156 factory codes — covering 98% of tyres worldwide.
Enter DOT Code
Full code, partial code, or just what you can read
Enter the complete code or just the last 4 digits · Where do I find this?
💡 Tip: Date code alone tells you age. Plant code alone tells you manufacturer. Both gives full picture.
📍 Where to Find Your DOT Code
What Each Part Means
Only the last 4 digits matter for age. Enter them above to calculate your tyre's exact age.
Check Outer Sidewall First
Asymmetric tyres: Full DOT code with date is always on the outboard (outside) sidewall — you can see it without removing the wheel.
Symmetric/Directional Tyres
May have date code on either side. The partial DOT (no date) often appears on both sides, but complete code with date is usually only on one.
Find Last 4 Digits
The date code is the last 4 digits (e.g., 2419 = week 24, 2019). If you only see 3 digits, see our decade guide below.
Worn or Damaged?
Use our partial code input above — enter just the plant code OR date code if the rest is unreadable.
📅 DOT Date Codes by Decade — Visual Examples
The DOT code format has changed over the years. Here's how to read codes from different eras with examples of what you'd actually see on the tyre:
💡 Quick Rule
3 digits = Pre-2000 = Replace immediately. Don't waste time calculating exact age — any 3-digit code means the tyre is at least 25 years old and unsafe.
📜 History of the DOT Code — With Examples
The DOT code exists because of tragedies. Here's how it came to be on every tyre, with examples of what codes looked like at each stage:
Week 24, year ending in 7 → Could be 1977, 1987, or even 1997!
Week 24, 199? — The ▲ means 1990s, but is it 1993 or 1997?
Week 24, year 2000 — Clear! Works until 2099.
Week 24, year 2025 — This tyre is brand new!
Is DOT Required on Every Tyre?
| Tyre Type | DOT Required? | Max Recommended Age | Notes |
|---|---|---|---|
| 🚗 Passenger Car | ✓ Yes | 10 years | Standard recommendation worldwide |
| 🏍️ Motorcycle | ✓ Yes | 5-7 years | Higher stress, more critical — many riders replace at 5 years |
| 🚐 Caravan/Motorhome | ✓ Yes | 5-7 years | Often sits unused + UV exposure = ages faster than driven tyres |
| 🚛 Truck/18-Wheeler | ✓ Yes | 7-10 years | Retreading complicates age assessment. Check casing age. |
| 🚜 Agricultural/OTR | Usually | Varies | Enforcement varies. Many have DOT, some don't. |
| 🚲 Bicycle | ✗ No | N/A (no standard) | Premium brands sometimes include date codes. Rubber still degrades. |
| ✈️ Aircraft | ✗ Different System | Cycles, not years | FAA/CASA uses takeoff/landing cycles, not calendar age. |
| 🏎️ Racing Slicks | Sometimes | Varies by compound | Marked "NOT FOR HIGHWAY USE" — competition rules apply instead. |
🔬 Why Tyres Age (The Science)
Tyres don't just wear out from driving — they degrade chemically over time, even sitting unused in a garage. Here's what happens:
🌡️ Oxidation
Rubber reacts with oxygen in the air. Over years, this breaks down the polymer chains that give rubber its flexibility. The tyre becomes brittle and hard.
☀️ UV Degradation
Sunlight accelerates aging significantly. Tyres stored outdoors or in sunny climates (Hawke's Bay, Nelson) age faster than those in shaded garages.
🌡️ Heat Cycling
Repeated heating and cooling (daily driving, seasonal changes) stresses the rubber compound, causing micro-cracks to form and propagate.
💨 Ozone Attack
Ozone in the atmosphere attacks rubber, causing characteristic "crazing" — fine surface cracks visible on sidewalls of aged tyres.
What Happens to Old Tyres?
- Reduced grip: Hardened rubber can't conform to road surface — less contact = less traction
- Longer braking: 6-9 year tyres add 10-20% to stopping distance. 10+ years can add 25%+ (try our simulator)
- Sidewall weakness: Cracks allow air loss and can lead to sudden blowouts at speed
- Tread separation: Degraded bonds between rubber layers can cause catastrophic failure
- Unpredictable handling: Aged tyres respond inconsistently, especially in emergency manoeuvres
Does Weight or Use Matter?
Common myth: "My tyres have low mileage, so they're fine."
Reality: Time degrades rubber regardless of use. A spare tyre sitting in your boot for 10 years is just as old as one driven 100,000 km. UV exposure and oxidation are the primary aging factors, not mileage or weight.
That said, environment matters:
- Indoor-stored tyres (warehouses, garages) age slower than outdoor-stored
- Climate-controlled storage is best — cool, dark, away from ozone sources (electric motors)
- Caravans and boats sitting in the sun age their tyres faster than daily-driven cars
🏎️ When Old Tyres Are Actually Wanted
Yes, some people prefer aged tyres! Here's the legitimate use case:
Drift & Track Practice
Racers and drifters often seek tyres that are 1-3 years old (not ancient, just "seasoned") because:
- Reduced grip = easier to initiate and control slides
- Predictable breakaway = more consistent lap times during practice
- Cost-effective = why destroy expensive fresh tyres learning?
- Hardened compound = lasts longer in abuse conditions
⚠️ Important: This is for controlled environments only (closed tracks, private property). Old tyres are never appropriate for road use or high-speed competition. Sidewall integrity still matters — check for cracks.
🏷️ Special Markings & OE Codes
Beyond the DOT code, many tyres have special markings indicating they were developed for specific vehicle manufacturers:
Original Equipment (OE) Markings
Pro tip: OE tyres shouldn't be mixed with non-OE versions of the same model. The compounds are different, which can affect handling balance.
Run-Flat Indicators
Run-flat tyres have reinforced sidewalls allowing limited driving after puncture. Look for these codes:
Different manufacturers use different codes. All mean the same thing: self-supporting technology.
Rare & Unusual Markings
- Treadwear/Traction/Temperature (UTQG): US grading system. Treadwear 400 = 4x baseline. Traction AA/A/B/C. Temperature A/B/C.
- M+S or M/S: Mud and Snow — meets basic winter requirements. Common but doesn't guarantee true winter performance.
- 3PMSF (Three Peak Mountain Snowflake): ❄️ The mountain/snowflake symbol means tested for severe winter conditions.
- XL or RF: Extra Load / Reinforced — higher load capacity, usually require higher inflation pressure.
- C or LT: Commercial / Light Truck — stronger construction for vans and utes.
- E-mark (E4, E11, etc.): European type approval. Number indicates which country tested it.
- Colored dots: Red dot = high point for matching. Yellow dot = light spot for valve alignment. (Factory use)
Understanding the DOT Code
🛑 How Tyre Age Affects Your Stopping Distance
Old tyres don't just look worn — they perform worse. As rubber ages, it hardens and loses grip, directly increasing your stopping distance.
Normal braking
+10-20% stopping
+25%+ stopping
At 100 km/h, that extra 25% could mean 15+ metres more to stop — the difference between stopping safely and a collision.
🚦 Tyre Age Safety Guide
Rubber degrades over time regardless of tread depth or kilometres driven. Here's what different ages mean for your safety on NZ roads:
🚨 Tyre Recall History & Safety Database
Tyre recalls have caused some of the deadliest vehicle safety crises in history. Understanding this history helps you appreciate why checking your tyres matters.
⛔ The Firestone-Ford Crisis (2000) — The Recall That Changed Everything
🔍 How It Was Discovered
The crisis unfolded over years, with warnings ignored until tragedy forced action:
- 1996: Personal injury lawyers first aware of accidents, but didn't report to NHTSA fearing it would compromise lawsuits
- 1996: Arizona state government told Firestone their treads were separating in high temperatures — Firestone sent engineers who blamed "customer misuse"
- 1999: Ford quietly replaced tyres in Saudi Arabia, Venezuela, Malaysia, Thailand — but didn't report to US regulators
- February 2000: KHOU-TV Houston investigative reporter Anna Werner broke the story, revealing the pattern of failures
- May 2, 2000: NHTSA finally opened formal investigation after the news coverage
- August 9, 2000: Firestone announced recall — but only after retailers (Sears, Discount Tire) had already stopped selling the tyres
📋 Detailed Timeline
❓ What Went Wrong
Root causes identified:
- Manufacturing defects: Poor adhesion between tread and steel belts at Decatur plant
- Design issues: Tyre ran hotter than Goodyear equivalents, small wedge angle
- Ford's pressure recommendation: 26 PSI (Firestone recommended 30 PSI) to mask Explorer's rollover tendency
- Heat + Speed: 80% of failures in hot states (FL, TX, CA, AZ) at highway speeds
- Tread separation: Belt edge lifted, causing rapid deflation and loss of control
Affected vehicles: Ford Explorer, Ranger, F-150, Mercury Mountaineer, Mazda Navajo
Financial consequences:
- Firestone: $800 million lawsuit settlements
- Ford: $590 million in settlements, 1,500+ cases settled
- Firestone paid Ford $240 million in 2005 to settle claims
- Individual fatality settlements: $4-8 million; paralysis cases: $12-16 million
Historical note: This wasn't Firestone's first major recall. In 1978, they recalled 14.5 million radial tyres at a cost of $100 million (about $387 million today) — it nearly bankrupted the company and made them vulnerable to Bridgestone's 1988 acquisition.
Recent Tyre Recalls (2024-2025)
Search by VIN, tyre brand, or DOT code
🏢 Who Owns Which Tyre Brand?
Understanding brand ownership helps you track recalls across related brands and understand manufacturing quality. Dates show when brands were founded and acquired.
💡 Why This Matters
- Recall tracking: A recall on Firestone affects Bridgestone plants — check both
- Quality consistency: Budget brands often use parent company technology
- Warranty support: Parent company backs subsidiary warranties
- Manufacturing overlap: Same plant may produce multiple brands
🏭 What Manufacturers Say About Tyre Age
Major tyre manufacturers have official positions on maximum tyre age. These are more conservative than many people realise:
🔬 What is ISO/IEC 17025?
The international standard for testing laboratory competence. Manufacturers with ISO 17025 certification (like Hankook, Apollo, BKT) have independently verified testing procedures. Anchee tyres (exclusive to Tyre Dispatch in NZ) are tested to ISO 17025 standards through their Yokohama partnership — view Anchee range.
⚠️ The Common Theme
Every major manufacturer agrees: 10 years is the absolute maximum, with inspections starting at 5-6 years. Don't let anyone tell you "they look fine" is an adequate assessment for tyres over 6 years old.
🇳🇿 Why NZ Tyres Age Faster — The Factors Manufacturers Don't Account For
Standard tyre age recommendations (5-year inspection, 10-year max) are developed in Europe, USA, and Japan — not for NZ conditions. Here's why you should be more conservative:
🌊 Salt Air & Marine Environment
NZ has one of the highest coastline-to-land ratios in the world. No point in NZ is more than 128km from the sea. This means salt-laden air reaches almost everywhere.
- Research confirms: "Salt spray causes swelling, loss of mechanical properties, and changes in chemical structure in rubber"
- Accelerated aging: "High-salt environments accelerate the aging process of rubber, reducing service life and performance"
- Coastal towns worst: Tauranga, Wellington, Auckland, Napier — constant salt exposure
- Even inland areas: Prevailing westerlies carry sea salt across the country
Impact: Salt ions penetrate rubber, causing oxidation from the inside out — damage you can't see until it's too late.
🛣️ Poor Road Quality
NZ roads are among the worst in the developed world. This isn't opinion — it's data:
- Ranked 5th WORST of 59 developed countries (Zutobi 2022)
- Road Quality Index: 4.5/7 — only 48th globally
- Deteriorating: Roads got 9% worse in just 5 years (2014-2019)
- Only 50% of NZers rate our major roads as "good" (vs 60% global average)
- Infrastructure ranking: NZ ranks LAST among OECD for delivery
- No major cities connected by 4-lane highways (unique among OECD)
Impact: Potholes, rough surfaces, and poor maintenance cause more mechanical stress, heat buildup, and sidewall damage.
☀️ Extreme UV Radiation
NZ has some of the highest UV levels in the world due to ozone layer thinning over the Southern Hemisphere and clean, unpolluted air.
- 40% higher UV than equivalent Northern Hemisphere latitudes
- Peak UVI 13+ common in summer (extreme rating starts at 11)
- UV causes: Photo-oxidation, surface cracking, rubber hardening
- Worst regions: Hawke's Bay, Nelson, Marlborough, Central Otago
Impact: UV breaks down polymer chains in rubber compound, causing surface cracking that spreads inward over time.
🌡️ Extreme Temperature Cycling
NZ's maritime climate means rapid temperature swings — often 15-20°C changes in a single day.
- "Four seasons in one day" — Wellington, Christchurch common
- Thermal cycling: Expansion/contraction stresses rubber
- Central NZ worst: -5°C to +25°C swings inland
- Research shows: Temperature fluctuation accelerates degradation
Impact: Repeated expansion/contraction weakens the bonds between rubber layers and the steel belts.
📋 Our NZ-Adjusted Tyre Age Recommendations
Based on NZ's unique environmental factors, we recommend earlier replacement than standard manufacturer guidelines:
⚡ Bottom line: Manufacturer recommendations are for ideal conditions. NZ conditions are far from ideal. When Michelin says "10 years max," that assumes European roads and climate — not salt-laden coastal air, potholed highways, and extreme UV. Subtract 2-3 years from any standard recommendation for NZ.
🛣️ NZ's Most Dangerous Roads — Where Tyre Condition Matters Most
On high-risk routes, the difference between new and aged tyres can be life or death. Here's where NZ road safety data shows the highest crash rates — and how to stay safe:
⚠️ Why It's Dangerous:
- Steep grades: 8%+ climbs put stress on brakes and tyres
- Tight curves: Winding road follows Wairoa River valley
- Single carriageway: No median barrier, head-on risk
- Weather: Fog, rain, and ice in winter — summit often in cloud
- Heavy trucks: Major freight route = speed differentials
- Dangerous intersections: Belk Rd junction inside a bend in 100km/h zone
🕐 Worst Times:
- 4-6pm weekdays: Commuter traffic meets tired drivers
- Friday evenings: Weekend exodus from Tauranga
- Early morning winter: Black ice, fog, low visibility
✅ Prevention Tips:
- Check tyre pressure before climbing — heat from braking increases pressure
- Use engine braking on descent, don't ride the brakes
- Allow 10+ minutes extra, don't rush to overtake
- Consider SH2 via Paeroa in bad weather (longer but safer)
⚠️ Why It's Dangerous:
- High traffic volume: Main north-south route, constant flow
- Single carriageway: Most sections have no median barrier
- Limited passing: Frustration leads to risky overtakes
- Fatigue: Long straight sections cause driver drowsiness
- Tourist traffic: Unfamiliar drivers, campervans
🕐 Worst Times:
- Public holidays: Auckland exodus north
- Sunday afternoons: Return traffic, tired drivers
- 2-4am: Fatigue crashes on empty road
✅ Prevention Tips:
- Stop every 2 hours — Kaiwaka, Brynderwyn rest stops
- Avoid peak holiday travel times (leave early morning)
- Fresh tyres essential — long distances at speed
- Watch for "Revive Zone" signs — pull over if drowsy
⚠️ Why It's Dangerous:
- SH1/SH29 intersection: Called "one of NZ's most dangerous intersections"
- T-junction design: Right turns across 100km/h traffic
- Speed compliance: 100→60km/h drop often ignored
- Peak congestion: Queue backs up, rear-end crashes
- Truck traffic: Bay of Plenty freight meets Waikato traffic
🕐 Worst Times:
- 4-6pm weekdays: Intersection backs up significantly
- Morning rush: Hamilton/Tauranga commuters
✅ Prevention Tips:
- Approach intersection with caution even on green
- Use slip lane to merge — don't cut across
- Roundabout upgrade planned — check NZTA for updates
- Good brakes and tyres essential — sudden stops common
⚠️ Why It's Dangerous:
- High commuter load: Pukekohe growth outpaced road capacity
- Narrow shoulders: No room for error
- Multiple accesses: Driveways, side roads, farms
- Speed vs design: 80-100km/h limits on inadequate road
🕐 Worst Times:
- 7-9am, 4-6pm: Commuter rush both directions
- Wet weather: Poor drainage in sections
✅ Prevention Tips:
- Consider train from Pukekohe during peak times
- Maintain 4-second following distance
- Watch for vehicles pulling out from driveways
⚠️ Why It's Dangerous:
- Industrial traffic: Refinery trucks, port traffic
- Intersection conflicts: Multiple side roads
- Speed differential: Heavy vehicles vs cars
✅ Prevention Tips:
- Give trucks extra space — they can't stop quickly
- Watch for wide loads exiting industrial areas
📊 NZ Road Safety Facts
- 2024: Lowest per capita road death rate in 100+ years — but still 300+ deaths annually
- Rural vs Urban: 257 rural deaths vs 91 urban (2019) — tyres matter more on highways
- Road quality: Only 5% of NZ roads are median-divided, 20% have forgiving roadsides
- Social cost: NZD $9.77 billion annually (3% of GDP)
Local relevance: If you're driving the Kaimais regularly from Tauranga, or commuting on SH1/SH29, your tyres are working harder than average. The steep grades, curves, and wet conditions demand more from your rubber. Don't compromise on tyre age or condition.
💰 Tyre Replacement Economics Calculator
Should you replace now or wait? Factor in fuel economy loss, risk costs, and replacement timing to make an informed decision.
Calculate Your Break-Even Point
Risk Cost Estimates (NZ)
Minor Incident
Moderate Incident
Severe Incident
📊 NZ Driving Data Used
- Average annual km: 11,500-14,000 km (combustion vehicles)
- Rolling resistance impact: 10% increase in RR = 1-2% fuel economy loss
- Tyre aging effect: Aged rubber increases rolling resistance as compound hardens
- Industry standard: 14,000 km/year × vehicle age = expected odometer reading
⛽ How Tyre Age Affects Your Fuel Economy
Old tyres don't just affect safety — they cost you money at the pump every time you fill up.
Rolling Resistance Basics
Rolling resistance accounts for ~20% of total fuel consumption. As tyres age, rubber hardens, flexibility decreases, and rolling resistance increases.
The Numbers
10% increase in rolling resistance = 1-2% fuel economy loss. Over a year of driving, that's $50-$150 in extra fuel costs.
Pressure Matters Too
Underinflation by 0.3 bar = +6% rolling resistance. By 1.0 bar = +30% rolling resistance. Aged tyres lose pressure faster.
🔄 The Counter-Intuitive Truth About New vs Worn Tyres
New tyres actually have higher rolling resistance than worn tyres (deeper tread = more flex = more resistance). You may see a 2-4% MPG decrease when fitting new tyres. However, aged tyres (hardened rubber) have increased rolling resistance that compounds the problem. The sweet spot is newer tyres with some wear — but never sacrifice safety for economy.
🏎️ Speed Rating & Load Index Guide
The DOT code tells you when and where your tyre was made. But other sidewall markings tell you what your tyre can handle:
Speed Ratings
The letter after your tyre size indicates maximum safe speed.
| Rating | Max Speed | Typical Use |
|---|---|---|
| Q | 160 km/h | Light truck, winter tyres |
| S | 180 km/h | Sedans, vans |
| T | 190 km/h | Family sedans ⭐ Common |
| H | 210 km/h | Sport sedans ⭐ Common |
| V | 240 km/h | Sports cars ⭐ Common |
| W | 270 km/h | High-performance |
| Y | 300 km/h | Supercars |
| (Y) | 300+ km/h | Track-focused |
Load Index
The number indicates maximum weight per tyre.
| Index | Max Load | Typical Use |
|---|---|---|
| 75 | 387 kg | Small cars |
| 82 | 475 kg | Compact cars |
| 91 | 615 kg | Sedans ⭐ Common |
| 94 | 670 kg | Family cars ⭐ Common |
| 100 | 800 kg | SUVs, wagons |
| 106 | 950 kg | Large SUVs |
| 112 | 1,120 kg | Light trucks |
| 121 | 1,450 kg | Commercial vehicles |
📍 Where to Find These on Your Tyre
Look for the size string: 205/55R16 91V — here "91" is the load index and "V" is the speed rating. This is separate from the DOT code (which shows manufacture date).
⚠️ NZ WOF Requirements
Speed rating must match or exceed your vehicle's maximum speed capability. Fitting lower-rated tyres will fail WOF. Load index must support the vehicle's gross axle weight rating. Check your door jamb placard for specifications.
🚗 NZ WOF Tyre Requirements — VIRM Section 4.2
What the Warrant of Fitness inspector actually checks, per Waka Kotahi VIRM. For a complete guide covering all WOF requirements (not just tyres), see our comprehensive NZ WOF Guide.
✅ Tread Depth
Minimum 1.5mm across 75% of tread width, around entire circumference. For winter tyres (snowflake symbol): minimum 4mm.
✅ Same-Axle Matching
Tyres on the same axle must match: same size, same carcass type, same pattern. Different brands are OK if these match.
✅ Size Limits
Maximum 5% diameter increase from original without LVV certification. Larger requires engineering sign-off.
⚠️ Condition
No cracking, perishing, bulges, cuts, or exposed cords. This is where age becomes a factor — older tyres show these signs.
⚠️ Speed Rating
Must match or exceed vehicle's maximum speed capability. Lower-rated tyres = automatic fail.
❌ No Age Limit (But...)
NZ has no explicit age limit, but tyres 8-10+ years almost always show condition issues that fail inspection.
🔍 Wear vs Age Correlation
NZ average: 11,500-14,000 km/year. Use this to assess if your tyres are wearing normally:
- 5-year tyre with 70,000 km: Normal wear pattern — age and use are aligned
- 6-year tyre with 20,000 km: ⚠️ Underused — aging rubber is a bigger concern than wear
- 3-year tyre with 60,000 km: High use — check tread depth, but rubber is still fresh
Key insight: Low-mileage doesn't mean safe. A spare tyre sitting for 10 years has the same age risk as one driven 100,000 km.
Basic Questions
Age & Safety
Vehicle Types
NZ-Specific Questions
Buying & Economics
Special Cases
🛠️ More Free Tools
❓ Quick FAQ
Essential questions answered. For 25+ detailed questions, see our Complete FAQ above.
Time for New Tyres?
If your tyres are past their prime, don't wait for a WOF failure. Old tyres = longer stopping distances = more risk. We stock quality brands with fresh manufacturing dates — including our exclusive ranges:
Built by Taylor Houghton — Tyre Dispatch
This calculator was designed and developed by Taylor Houghton, Director of Tyre Dispatch and Manager of Traction Tyres Ltd. With a hands-on approach to tyre safety education, Taylor built this tool to help Kiwi drivers understand their tyres without the jargon — because knowing your tyre's age shouldn't require a degree.
Other tools developed by Taylor include the Tyre Braking Simulator, PSI Calculator, Tyre Size Calculator, WOF Axle Checker, and the AI-powered tyre scanner. Taylor also appeared in the official Tyrewise launch video, advocating for responsible tyre disposal in New Zealand.
🚗 Quality tyres, straight-up advice, free North Island delivery.
📍 Based in Te Puke, Bay of Plenty — serving Kiwi drivers since 2007.
