The sidewall of a tyre shows all the basic information of a tyre. It can be considered as the "identity card" of the tyre.
Typical markings as found on a tyre are illustrated:
1. Tyre section width in mm.
2. Section height to section width relation in %.
3. Tyre construction (R= Radial).
4. Rim diameter in inches.
5. Maximum load capacity (load index)
6. Speed symbol
7. TUBELESS tyre.
8. ECE Type approval mark and number.
9. Location of treadwear Indicator.
10. M&S (Mud & Snow) Winter capabilities.
11. Tested and qualified for Severe Snow Usage.
12. Production date (week, year : decade 1990-1999 ).
13. Department of Transportation compliance symbol.
14. D.O.T. manufacturer code.
15. Country of manufacture.
16. Trade name.
17. Tyre construction details (D.O.T.).
18. Load and pressure marking (D.O.T.).
19. Tyre type (radial).
20. Mark required by U.S.A. Consumer information regulations (Quality Grade).
21. Location of winter tread wear indicator
Position 1: The tyre section width is the linear distance in millimetres between the outsides of the sidewalls of an inflated tyre excluding elevations due to labelling (markings), decorations, or protective bands or rims.
Position 2: Section height is half the difference between the overall diameter and the nominal rim diameter. In the course of tyre history the shape of the tyre has changed from an almost circular tyre to flatter, wider tyres. This has changed the relationship or aspect ratio (A/R) of the tyre section height to the section width from 100% to 70%, 60%, 50%, and even lower.
Position 3: The tyre construction of a radial tyre is indicated by the letter "R" within the size marking on the sidewall.
Position 4: Rim diameters have increase in the last decades. Whereas a 16" rim was considered as exceptional 10 years ago, today 16" rims are very common.
Position 5: The load rating of a tyre is a numerical indication of the maximum load that a tyre can carry at the speed indicated by its speed symbol and at a given inflation pressure. However, it must be noted that all load ratings, regardless of the tyre speed symbol, are for a maximum of 210 km/h (130 mph). After this speed the maximum load rating should be reduced.
Some tyres, notably ZR rated, do not carry a service description. In this case it is advisable to consult the tyre manufacturer to determine maximum loads applicable.
Position 6: The speed symbol of a tyre forms part of the load index and is a letter or that indicates the maximum speed at which the tyre can carry a load corresponding to its load index (except for speeds above 210 km/h).
Load indices and speed symbols are shown on both tyre sidewalls. The first number denotes the tyre load carrying capacity in SINGLE application, while the second number refers to DUAL fitment.
M&S (winter) tyres with a lower speed rating than that of the vehicle may be fitted. In some countries it is mandatory that a sticker be placed in the view of the driver indicating the maximum speed of the tyre. This speed may not be exceeded while these tyres are fitted.
Position 7: The word "TUBELESS" indicates the tyre is to be used without a tube.
Position 8: ECE Type approval mark and number confirms that the tyre conforms to the requirements of the ECE regulation R30.
Position 9: Shows the location of the treadwear indicators (1.6 mm high) in the principal grooves of the tyre tread. If the tyre is worn to the point that the treadwear indicators are at the same height as the adjacent tread ribs, this means that the tyre has only 1.6mm of tread depth left. You should replace your tyres immediately, as 1.6 mm is the legal minimum tread depth required by law.
Position 10: The letters "M&S" show that the tyre is a winter tyre or has snow and ice capabilities.
Position 11: Tyre has been tested for 'severe snow usage' in accordance with ISO test procedures, has been found acceptable and is certified as such.
Position 12: Prior to 2000, the production date of the tyre was shown as 3 digits at the end of the serial number, the first two being the week of production, the third, production year. The decade, 1990 - 1999, is indicated with a ◄. Since the year 2000, 4 digits are used, the third and fourth together being the production year.
Position 13: The "DOT" symbol indicates conformity to U.S.A. tyre regulations.
Position 14: The D.O.T. manufacturer's code is a coded value for the tyre construction and identification in accordance with U.S.A. regulations.
Position 15: Country of manufacture indicates tyre production origin.
Position 16: Trade name of the tyre (includes family name and design name, i.e. 'Carat Exelero', Carat Attiro', 'Diadem Linero', etc.).
Position 17: Tyre construction details required for the Department of Transportation in the U.S.A.(D.O.T.).
Position 18: The maximum load capacity and inflation pressure in accordance with U.S.A., CANADA, AND AUSTRALIA regulations.
Position 19: Tyre is a "RADIAL" construction.
Position 20: Marking required by U.S.A. Consumer regulation for Uniform Tyre Quality Grading (U.T.Q.G.).
Position 21: Shows the locations of the winter tread wear indicators (4 mm high) in the principal grooves of the tyre tread. If the tyre is worn to the point that the winter wear indicators are at the same height as the adjacent tread ribs the tyre has only 4mm of tread left. It is generally recommended to replace winter tyres with less than 4mm-profile depth, to ensure optimum safety in winter conditions.