Tyre Size Finder
How to read a tyre size
Tyre sizes follow an international standard format. Here's how to decode a common size like 205/55R16 91V:
NZ tyre rules and WOF requirements
New Zealand has specific rules about tyres that are checked during your Warrant of Fitness (WOF) inspection:
1.5mm across all principal grooves around the full circumference. NZ's limit is 1.5mm — lower than the 1.6mm standard in the UK, EU, and Australia.
Tyres must be free from cuts, bulges, or exposed cords. Repairs must be properly done — plugs visible from the outside are not acceptable for WOF.
Tyres on the same axle must be the same size and type (both radial or both crossply). Mixing radial and crossply on the same axle will fail a WOF.
NZ has no legal tyre age limit, but rubber degrades over time. Most manufacturers recommend replacing tyres after 6-10 years regardless of tread depth. Check the DOT date code on the sidewall.
When to replace your tyres
While 1.5mm is the legal minimum in NZ, experts recommend replacing tyres at 3mm. At 1.6mm tread depth, wet braking distances are already significantly longer than new tyres. Here's a guide:
| Tread Depth | Status | Action |
|---|---|---|
| 8mm (new) | Excellent | No action needed |
| 4-6mm | Good | Monitor regularly |
| 3-4mm | Fair | Start shopping for replacements |
| 1.5-3mm | Low | Replace soon — reduced wet grip |
| Below 1.5mm | Illegal | Replace immediately — WOF failure |
Frequently Asked Questions
How do I read a tyre size?
A tyre size like 205/55R16 means: 205 is the width in mm, 55 is the aspect ratio (sidewall height as a percentage of width), R means radial construction, and 16 is the wheel diameter in inches. You'll also see a load index and speed rating after these numbers (e.g. 91V).
Where can I find my current tyre size?
Check the sidewall of your current tyres — the size is printed in large text. You can also find the recommended tyre size on a sticker inside the driver's door jamb, in your vehicle owner's manual, or on the tyre placard (usually inside the fuel filler flap or glove box).
What is the minimum tyre tread depth in New Zealand?
The NZ legal minimum tread depth is 1.5mm across the principal grooves around the full circumference of the tyre. This is checked during your WOF inspection. For safety, most experts recommend replacing tyres at 3mm, as wet braking distances increase significantly below this point.
Can I use a different tyre size than what's recommended?
You can use a different tyre size, but the overall rolling diameter should stay within 2-3% of the original to avoid speedometer inaccuracy. Changing to a wider tyre can affect handling and fuel economy. Significantly different sizes may cause a WOF failure. Always check with a tyre specialist.
How often should I check my tyre pressure?
Check tyre pressure at least once a month and before long trips. Under-inflated tyres wear unevenly, increase fuel consumption by up to 3%, and reduce handling safety. The recommended pressure is on the tyre placard inside the driver's door or fuel filler cap — not the maximum pressure printed on the tyre sidewall.
Do I need winter tyres in New Zealand?
NZ doesn't require winter tyres by law, but they're recommended if you regularly drive in snow or ice — especially in the South Island highlands or central North Island in winter. Chains are required for some alpine passes and ski field roads. All-season tyres are a good compromise for most NZ conditions.
Tyre rules from NZTA Vehicle Inspection Requirements. Tyre specifications from Wheel-Size.com.