Car tyres Understanding tyre markings
Understanding the markings on the sidewalls of your car tyres will help you choose the right replacements for your car.
The letters and numbers on the side of your car tyres relate to their size, dimensions, composition and capabilities.
Here’s what each section of the code means, using the tyre size and specification 175/65 R14T as an example:
- 175 Tyre width in mm
- 65 Tyre sidewall profile – sidewall height expressed as a percentage of its width
- R Radial (rather than a cross ply)
- 14 Diameter of the wheel rim, in inches
- T Speed rating which must match or exceed the maximum speed of your car.
Discover the Best Buy tyres that came top in our tests
Car tyre speed ratings
- S 180km/h or 112mph
- T 190km/h or 118mph
- U 200km/h or 125mph
- H 210km/h or 130mph
- V 240km/h or 149mph
- W(ZR) 270km/h or 168mph
- Y(ZR) 300km/h or 186mph
- ZR Above 240km/h or 149mph
So the tyre we used as an example is only suitable for use on cars with a maximum speed of 118mph (or less). Tyres available in this size and specification include the Dunlop SP 30, Firestone's Multihawk and the Continental EcoContact 3.
Your car’s handbook will tell you the minimum tyre speed and load ratings you should go for. Once you know the size and type of tyre you need, head over to our tyre reviews to find the best tyres we've tested.
Elsewhere on your tyres you will see the manufacturer’s name, the name of the tyre model and information about where and when the tyre was made.
Run-flat tyres help you avoid this, although they are more expensive
Run-flat tyres are increasingly popular. If you have a puncture on your journey, a run-flat tyre supports the vehicle weight so you can travel for another 50 miles or so, at a maximum speed of 50mph.
There are many markings that could indicate your tyre is a run-flat tyre, including DSST, RFT, ROF and RunFL.
Run-flat tyres and traditional car tyres should not be mixed on the same car, as it could affect the handling.
Tyresafe advises run-flat tyres should not be used on cars without a tyre pressure monitoring system, which is used to alert you of a deflation or puncture.
It also warns against using run-flat tyres when towing, as they're only designed to support the weight of the vehicle itself.