Your tyre sidewall is packed with information — far more than just the size code. From the manufacture date to the tread wear grade, understanding these markings helps you make better decisions about tyre safety, replacement timing, and purchasing. This guide covers everything you'll find on a modern tyre sidewall.
The Tyre Size Code
The most prominent marking is the tyre size — for example, 205/55R16 91V. This tells you the width, aspect ratio, construction type, rim diameter, load index, and speed rating. See our complete tyre size guide for a full breakdown of each element.
The DOT Code — and How to Find Your Tyre's Age
Every tyre sold in the US and many other markets (including NZ imports) carries a DOT (Department of Transportation) code. It starts with the letters "DOT" followed by a series of characters. The most important part for NZ drivers is the last four digits, which encode the manufacture date.
For example: DOT XXXX XXXX 2419 — the "2419" means the tyre was manufactured in the 24th week of 2019.
Why does this matter? Tyres age even if they're not used. The rubber compound degrades over time, becoming harder and more prone to cracking. Most tyre manufacturers and safety organisations recommend replacing tyres that are more than 6 years old, regardless of tread depth, and consider tyres over 10 years old to be unsafe regardless of appearance.
This is particularly important when buying used tyres or vehicles — always check the DOT date before purchasing.
UTQG Rating (Treadwear, Traction, Temperature)
Many tyres carry a UTQG (Uniform Tyre Quality Grading) rating, which provides a standardised comparison of tyre performance across three categories:
| Category | What It Measures | Example |
|---|---|---|
| Treadwear | Relative tread life compared to a reference tyre (100 = baseline) | 400 = 4× the reference tyre's life |
| Traction | Wet braking performance (AA, A, B, C — AA is best) | AA = excellent wet grip |
| Temperature | Heat resistance at sustained speed (A, B, C — A is best) | A = highest heat resistance |
A typical all-season tyre might be rated 500 A A — meaning excellent tread life, excellent wet traction, and excellent heat resistance. A high-performance summer tyre might be 200 AA A — shorter life but outstanding grip.
Tread Wear Indicators (TWI)
Look inside the main tread grooves and you'll see small raised rubber bars — these are tread wear indicators (TWI). They're moulded at exactly 1.6mm depth, which is the legal minimum tread depth in New Zealand.
When your tread wears down to the level of these bars, the tyre has reached its legal limit and must be replaced. You can also find the TWI location by looking for a small triangle (▲) or "TWI" marking on the sidewall — this points to where the indicator is located in the groove.
Note that 1.6mm is the legal minimum, not the safety minimum. At 1.6mm, wet braking distances increase significantly. Most tyre experts recommend replacing tyres at 3mm for optimal wet weather safety. Use our tyre checker tool to assess your tread depth.
M+S and the Three-Peak Mountain Snowflake
You may see one or both of these symbols on your tyre sidewall:
- M+S (Mud and Snow) — indicates the tyre meets minimum standards for mud and light snow use. Most all-season tyres carry this marking. However, it's a relatively low bar and doesn't indicate a true winter tyre.
- Three-Peak Mountain Snowflake (3PMSF) — a mountain with a snowflake symbol. This indicates the tyre has passed a more rigorous winter performance test and is suitable for serious winter conditions. If you drive in alpine areas or on the Crown Range in winter, look for this symbol.
Maximum Inflation Pressure
The sidewall shows a maximum inflation pressure — for example, "Max. Press. 44 PSI (300 kPa)". This is not the recommended operating pressure. It's the absolute maximum the tyre can safely hold.
Your correct operating pressure is on the door jamb sticker or in your owner's manual — typically 30–36 PSI for most passenger cars. Never inflate to the sidewall maximum for everyday driving.
Direction of Rotation
Many modern tyres — particularly performance and run-flat tyres — are directional, meaning they must be fitted to rotate in a specific direction. Look for an arrow on the sidewall labelled "Rotation" or "Direction". If fitted in the wrong direction, the tyre's drainage channels won't work correctly, significantly reducing wet weather grip.
Directional tyres can only be swapped front-to-rear on the same side of the car. They cannot be cross-rotated (left to right) without dismounting and remounting the tyre.
Inside / Outside Markings
Some tyres are asymmetric — they have different tread patterns on the inner and outer halves. These tyres are marked "Inside" and "Outside" on the sidewall. The "Outside" face must always face outward. Fitting an asymmetric tyre the wrong way around significantly reduces its performance and can be dangerous.
Unlike directional tyres, asymmetric tyres can be cross-rotated (left to right) as long as the inside/outside orientation is maintained.
Need help choosing the right tyre? Ask Charlie AI or browse by vehicle or tyre size.