Beyond the size, a tyre sidewall carries a dozen other codes. Most drivers ignore them, but several change whether a tyre is right for your car, and one of them is a legal matter.
Load and construction markings
- XLExtra Load, sometimes written Reinforced or RF. A stronger casing that carries more weight at the same size. Common on SUVs, vans, estates and electric cars.
- CCommercial. Built for van and light truck loads. Often paired with a double load index like 104/102.
- RRadial construction, which is what nearly every modern tyre is.
- ZRRadial rated above 149mph. You will see it on performance tyres.
If your car came with XL tyres, fit XL tyres. A standard casing in the same size is not equivalent and may be below the load rating your vehicle requires.
Run flat markings
Run flat tyres have reinforced sidewalls that support the car after a puncture, typically for up to 50 miles at up to 50mph. Manufacturers each use their own abbreviation:
- RFTBridgestone
- ROFGoodyear, Dunlop
- SSRContinental
- ZPMichelin
- EMTGoodyear
- DSSTDunlop
If your car was built for run flats it probably has no spare wheel and relies on a pressure monitoring system to tell you when one has deflated. Fitting standard tyres to such a car leaves you with no spare and no run flat capability.
Winter and snow markings
- M+SMud and snow. Self declared, no test, no standard. Means very little on its own.
- 3PMSFThree peak mountain snowflake. Independently tested for severe snow. This is the marking that European winter tyre laws recognise.
- Ice gripA mountain with an icicle. Tested specifically for braking on ice, mainly seen on Nordic tyres.
Manufacturer approval marks
A small letter or symbol next to the size means the tyre was developed and homologated for a particular vehicle manufacturer:
- MOMercedes
- AOAudi
- N0 N1 N2Porsche
- *BMW, Mini
- JJaguar
- VOLVolvo
These are approvals, not restrictions. A tyre without the mark is not illegal or unsafe on that car, provided the size, load index and speed rating are correct. The approved version was simply tuned alongside that car's suspension.
The DOT code
The four digits at the end of the DOT sequence give the manufacturing date. 2723 means week 27 of 2023. Use it to check the age of tyres on a used car, and on your spare, where age is usually what ends the tyre's life rather than wear.
Direction and fitting markings
- RotationAn arrow showing which way the tyre must turn. Fitting it backwards ruins wet performance.
- Outside / InsideAn asymmetric tyre with a specific face that must point outward.
- TWIMarks where the tread wear indicator bars sit in the grooves.
Directional and asymmetric tyres cannot simply be swapped side to side when rotating. Front to back on the same side only.