Tyre sidewall markings include a considerable amount of information. The tyre size and service description information is especially important where you are assessing wether tyres are suitable for specific vehicles. The information contained in this article is designed to provide meaning to the most important markings. For assistance in choosing replacement tyres, contact your Toyo tyre dealer.
Often the tyre brand is also the name of the manufacturer, but not always.
The tread pattern can be a name , or a number, a combination of letter and numbers, or a combination of a name and letters and numbers.
Tyre Size and Service Description
These two markings are usually located next to each other, as shown below. The service description is made up of two parts, a load index and speed rating.
Section Width: Width of the tyre in mm, from the widest points of the tyre, from sidewall to sidewall.
Aspect Ratio: The aspect ratio is the dimensional relationship of the section height compared to the section width, expressed as a percentage. In approximate terms The section height is the height of the tyre sidewall.The section height is calculated by: overall diameter less rim diameter, divide by 2.
To calculate the aspect ratio or tyre profile:
Section Height x 100
Casing Construction: The "R" designates the tyre has a radial casing construction. Bias-ply construction is indicated by "-" or "D"
Rim Diameter: The rim diameter in inches
Load Index: An index number indicating the tyre's maximum load capacity at its maximum rated speed and inflation pressure. The load index table will provide the corresponding load in kilograms or pounds. For this tyre the load index is 96, which is equivalent to 710kg. In Australia, ADRs and state regulations require that the tyres fitted to your vehicle have a load index that is equivalent or higher than the load index either stated or described on the tyre placard attached to your vehicle. The tyre placard can be found in the door jam, glove box, or for some vehicles under the fuel filler cap or bonnet.
Service Description: Describes the load index and speed rating when expressed together, as shown.
Uniform Tyre Quality Grading System
The Uniform Tyre Quality Grading System or UTQG is a system developed by the U.S. government to provide consumers with information regarding tyre tread wear, traction and operating temperature resistance. UTQG ratings are required for passenger car construction tyres sold in the U.S., therefore there are many tyres available in Australia that do not have UTQG Ratings.
Treadwear Rating: The tread wear grade is a comparative numerical rating based on the wear rate of the tyre when tested under controlled conditions on a specified test course. For example, a tyre with a treadwear rating of 200 would wear twice as well on this test compared to a tyre graded 100. Keep in mind that the actual using conditions of tyres in most cases vary greatly from the specified test course and test conditions, therefore tyre wear rates are normally different from those indicated by the UTQG treadwear rating.
Traction Rating: The traction rating indicates the tyre's ability to provide braking traction on wet pavement. This rating is determined using specific test conditions. The ratings are AA, A, B and C, with AA being the best.
Temperature Rating: The temperature indicates the tyre's ability to dissipate heat. The ratings are A, B and C, with A being the best.
Maximum Inflation Pressure and Load information
Tyres will often have the maximum rated load and inflation pressure marked on the tyre sidewall. These markings are not required for all tyre markets, therefore there are many tyres sold in Australia that will not have this information marked on the tyre sidewall. Where tyres are carrying the maximum rated weight, it is essential for user safety that the tyres are inflated to the maximum pressure. The maximum pressure shown is a cold inflation pressure, therefore the inflation pressure will increase after running. The maximum pressure is rarely the correct inflation pressure for most vehicles. For more information regarding inflation pressures, please refer to Tyre Tips regarding Inflation Pressure Maintenance.
Tyre Serial Number
Tyre serial numbers are applied to all tyres that are designed to be used on public roads, the format is industry standard as shown below.
Production week then year: The first two numbers indicate the production week, the second two numbers indicate the production year. For the example shown, the build date is 34th week, 2010. For tyres produced before 2000, the production week, then year used three characters only, the first two characters indicating the production week, the last character indicating the production year.
Tyre Construction Type
The tyre construction type can be indicated by a prefix on the tyre size, as shown below.
A "P" prefix indicates the tyre is passenger car construction. Passenger car construction tyres will have one load index.
An "LT" prefix indicates the tyre is light truck construction. Most light truck construction tyres will have tywo load indeces, one for fitment as a single tyre, and the second as a dual fitment, which will be a lower load index compared to the single fitment.
Many tyres will not have a prefix indicating the tyre construction type. A single load index will usually indicate passenger car construction. A dual load index or a tyre size suffix of "C" indicates the tyre is light truck or commercial tyre construction.
To ensure suitability of a tyre construction type for your vehicle, contact your Toyo tyre delaer.