A tyre sidewall is covered in numbers and abbreviations, and only some of them actually matter when you buy. Part of it is mandatory and set by regulation, part is a car manufacturer marking and part is simply marketing. Below are the markings that genuinely count when choosing a tyre.
Size, load index and speed rating
The largest number is the tyre size, for example 205/55 R16 91V. Here 205 is the width in millimetres, 55 the sidewall height as a percentage of that width, R radial construction and 16 the rim diameter in inches.
The number and letter after the size are the load index and speed rating. In the example 91 means the tyre carries up to 615 kg and V allows a maximum of 240 km/h. Both must be at least what the car manufacturer requires — a tyre with a lower index is not suitable even if the size matches.
A speed rating is not an invitation to drive fast; it is a construction limit. Winter tyres are in some cases allowed a lower speed rating than the car requires, but the driver then has to observe that limit.
Extra markings: XL, RF, M+S and OE codes
XL, or Extra Load, means a reinforced casing that carries more than a standard tyre of the same size. Where the car manufacturer requires an XL tyre, a standard casing must not be substituted.
The runflat marking differs by manufacturer: RF, RFT, ROF, ZP, SSR, DSST and others all mean the same technology. Fitting a runflat requires a suitable rim and a tyre pressure monitoring system.
M+S is the manufacturer own claim about mud and snow, with no mandatory test behind it. 3PMSF, the snowflake inside three peaks, is certified snow grip by comparison. For an Estonian winter look for 3PMSF, not M+S alone.
OE markings show the tyre was developed for a specific car maker: MO is Mercedes-Benz, AO Audi, a star BMW, N0 and N1 Porsche, VOL Volvo. These tyres are tuned to that car suspension. An OE-marked tyre also fits other cars when size and ratings match, and the absence of an OE marking is not a fault.
Usein kysytyt kysymykset
- What does 91V on a tyre mean?
- It is the load index and speed rating. The number 91 means the tyre carries up to 615 kg per tyre, and the letter V allows a maximum of 240 km/h. Both must be at least what the car manufacturer requires — a tyre with a lower index does not suit the car even if the size is right. The required ratings are in the owner manual or on the door pillar sticker.
- What does XL mean on a tyre?
- XL, or Extra Load, means a reinforced casing that carries more than a standard tyre of the same size. Heavier cars, SUVs and vans usually require them. Where the car manufacturer specified an XL tyre, it must not be replaced with a standard casing, because load capacity would then fall short of the requirement. The reverse substitution, XL in place of standard, is permitted.
- What is the difference between M+S and 3PMSF?
- M+S (Mud and Snow) is the manufacturer own declaration with no mandatory test behind it, so it does not prove real grip on snow. 3PMSF, the three-peak mountain snowflake, means snow grip tested and certified under UNECE R117. For an Estonian winter 3PMSF is a sensible minimum; M+S alone is not evidence of winter capability.
- Do I have to buy a tyre with an OE marking?
- No. An OE marking (MO, AO, star, N0, VOL and others) shows the tyre is tuned to a specific car maker and its suspension. If the car left the factory on such a tyre, the same marking gives the closest original feel, but a tyre without an OE marking is equally suitable when its size, load index and speed rating meet the requirement. A missing OE marking is not a shortcoming.