How to read a tire
The sidewall of a tire shows all the basic information of a tire. It can be considered as the "identity card" of the tire. Find here more information on the different markings of your tire.
There are various forms of tire size marking and these differ in order to differentiate between tire types.
The size markings should be treated the same as a part number on a vehicle, so the motorist should ensure that the tires on his vehicle carry the precise markings indicated in the vehicle handbook or are an approved alternative fitment (see TIRE CONVERSION). Most size markings indicate the dimensions, the type of structure and the speed capability of a tire.
1. Tire section width in mm
2. Section height to section width relation in %
3. Tire construction (R= Radial)
4. Rim diameter in inches
5. Maximum load capacity (load index)
6. Speed symbol
7. TUBELESS tire
8. ECE Type approval mark and number
9. Location of treadwear Indicator
10. M&S (Mud & Snow) Winter capabilities (see image below)
11. Snowflake winter icon (see image below)
12. Production date (week, year : decade 1990-1999 )
13. Department of Transportation compliance symbol
14. Serial number
15. Country of manufacture
16. Trade name
17. Tire construction details (D.O.T.)
18. Load and pressure marking (D.O.T.)
19. Tire type (radial)
20. Mark required by U.S.A. Consumer information regulations (Quality Grade)
21. Location of winter tread wear indicator
Position 10 and 11
Explanation of tire markings
Position 1 : The tire section width is the linear distance in millimetres between the outsides of the sidewalls of an inflated tire 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 tire history the shape of the tire has changed from an almost circular tire to flatter, wider tires. This has changed the relationship or aspect ratio (A/R) of the tire section height to the section width from 100% to 70%, 60%, 50%, and even lower.
Position 3 : The tire construction of a radial tire is indicated by the letter "R" within the size marking on the sidewall.
Position 4 : Rim diameters have increased 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 tire is a numerical indication of the maximum load that a tire 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 tire speed symbol, are for a maximum of 210 km/h (130 mph). After this speed the maximum load rating should be reduced. Some tires, notably ZR rated, do not carry a service description. In this case it is advisable to consult the tire manufacturer to determine maximum loads applicable. Find more information on this subject by visiting our load index page.
Position 6 : The speed symbol of a tire is a letter that indicates the maximum speed at which a given tire can carry the load indicated by the load index. Only those tires with a minimum speed rating as shown in the vehicle papers may be used on the vehicle (except for speeds above 210 km/h). Load indices and speed symbols are shown on both tire sidewalls. The first number denotes the tire load carrying capacity in SINGLE application, while the second number refers to DUAL fitment. M&S (winter) tires 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 tire. This speed may not be exceeded while these tires are fitted. Find more information on this subject by visiting our speed index page.
Position 7 : The word "TUBELESS" indicates the tire is to be used without a tube.
Position 8 : ECE type approval mark and number confirms that the tire conforms to the requirements of the ECE regulation R30/R54.
Position 9 : Shows the location of the treadwear indicators (1.6 mm high) in the principal grooves of the tire tread. If the tire is worn to the point that the treadwear indicators are at the same height as the adjacent tread ribs, this means that the tire has only 1.6mm of tread depth left. You should replace your tires immediately, as 1.6 mm is the legal minimum tread depth required by law. Find more information on this subject by visiting our Checking tire tread page.
Position 10 : The letters "M&S" show that the tire is a winter tire or has snow and ice capabilities.
Position 11 : Snowflake icon: tire has been tested for 'severe snow usage' in accordance with ETRTO test procedures, has been found acceptable and is certified as such.
Position 12 : Prior to 2000, the production date of the tire 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. tire regulations.
Position 14 : Tire serial number.
Position 15 : Country of manufacture indicates tire production origin.
Position 16 : Trade name of the tire (i.e. intensa hp, eskimo s3,…).
Position 17 : Tire 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 : Tire construction (R=radial).
Position 20 : Marking required by U.S.A. Consumer regulation for Uniform Tire 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 tire tread. If the tire is worn to the point that the winter wear indicators are at the same height as the adjacent tread ribs the tire has only 4mm of tread left. It is generally recommended to replace winter tires with less than 4mm-profile depth, to ensure optimum safety in winter conditions. Find more information on this subject by visiting our Checking tire tread page.
Tire dimension definition
You want to know more about tire dimension? Click on this link to get explanation on the basic tire and rim dimension nomenclature.
Tire companies throughout the world are members of regional tire manufacturer's associations (ETRTO for Europe), which establish tire dimensions and tolerances, load carrying capacities and inflation pressures for the different tire categories and sizes. The basic tire and rim dimension nomenclature is explained below:
Outside Radius (OR):The radius of an unloaded tire, mounted on its recommended rim and inflated to recommended pressure.
Section Width (SW):The width of the inflated tire section, on the measuring rim, excluding any lettering or decoration.
Section Height (SH):The distance from the bead seat to the outer tread contour of the inflated tire - at centreline.
Static Loaded Radius (SLR):The standing height from the road surface to the axle centre under nominal tire load/inflation conditions.
Loaded Section Width (LSW):The width of the loaded cross-section.
Aspect Ratio:The section height (SH) expressed as percentage of the section width (SW).
Minimum Dual Spacing:The minimum recommended distance between centrelines of dual mounted tires to avoid kissing in the flex area.
Rolling Circumference:The distance covered by one revolution of the tire (in mm). The rolling circumference of a tire is important for establishing the correct tire slippage relationship on 4-wheel drive vehicles using smaller tires on the front axle as well as assuring dimensional compatibility for tires used in dual mounted applications.
Tire size conversion
Tire size conversion consists in mounting a tire of a different size than the original equipment tire of the car. Before doing a size conversion you have to consider a number of points. You will find more information here.
Ensure that the tire which is to be mounted as a replacement to the original fitment has a load index and speed index equivalent to or higher than the original fitted tires (based on ETRTO: the European Tire and Rim Technical Organisation).
Respect the laws currently in effect.
Ensure that the diameter and width of the rims conform to the recommendations of ETRTO (tire and corresponding rim information can also be found in the rim manufacturer's documents) and correspond to the tire size chosen.
Ensure that the shock absorber's travel distance on the vehicle is sufficient in order to accept the replacement tire size without posing any mechanical or steering problem.
Remember that additional space is required if chains are to be fitted to the tires in the winter.
Changing to Corresponding Rims for different Series Aspect Ratio tiresWithin the scope of the previous mentioned basic rules it is possible to mount tires of a lower aspect ratio using a larger rim diameter. In order to maintain the same outside diameter of a tire it is necessary to increase the rim diameter. As the aspect ratio of a tire becomes smaller, the width of the tire increases.
In case of a rim change, it is important to respect exactly the same track distance of the original fitment as foreseen by he manufacturer.
All values concerning tire conversion do not constitute a professional binding agreement (manufacturer or distributor). The dealer and the end user are bound by law to respect obligatory regulations, technical instructions, directives from the vehicle manufacturer, the tire and rim manufacturers as well as legislative and regulatory authorities.
THE PERSON WHO PLACES THE VEHICLE IN CIRCULATION TAKES FULL AND ENTIRE RESPONSIBILITY ESPECIALLY CONCERNING TECHNICAL ROAD VEHICLE REGULATIONS
Load index
The load rating of a tire is a numerical indication of the maximum load that a tire can carry at the speed indicated by its speed symbol and at a given inflation pressure. Find here more details on the Load index of your vehicle.
The load rating of a tire is a numerical indication of the maximum load that a tire can carry at the speed indicated by its speed symbol and at a given inflation pressure. Please find here after a table with the corresponding maximum loads in Kg.
However, it must be noted that all load ratings are for a maximum of 210 km/h for a V rated tire, 240km/h for a W rated tire and 270km/h for a Y rated tire. After this speeds the maximum load rating should be reduced.
Some tires, notably ZR rated, do not carry a service description. In this case it is advisable to consult the tire manufacturer to determine maximum loads applicable.
In accordance with the European regulation (ECE-R54), all tires destined for commercial vehicles will be marked with a "Service Description" located near to the tire size marking. This consists of a code which indicates operating limits of load and speed and includes a "load index" for single and dual tire fitment and a "speed symbol" (e.g. 102/100R).
Load indices and speed symbols are shown on both tire sidewalls. The first number denotes the tire load carrying capacity in SINGLE application, while the second number refers to DUAL fitment.
An additional marking may be used to show the corresponding tire loads for an alternative higher speed. This additional marking will be placed in a circle.
Speed index
The speed index of a tire forms part of the load index and is a letter that indicates the maximum speed at which the tire can carry a load corresponding to its load index. You will find more information here.
The speed symbol of a tire forms part of the load index and is a letter that indicates the maximum speed at which a tire can carry a load corresponding to its load index. (Except for speeds above 210 km/h for a V rated tire, above 240 km/h for a W rated tire and above 270 km/h for a Y rated tire). Only those tires with a minimum speed rating as shown in the vehicle papers may be used on the vehicle.
Please see the following table with the different speed indices and their corresponding maximum speeds.
Winter tires with a lower speed index 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 tire. This speed may not be exceeded while these tires are fitted.
