Taking a close look at the sidewall of your tire can provide you with almost everything you really need to know about your tires. But, before we dive into tire language, let’s consider what kind of tires you have. Car tires are generally divided into the following main categories:
P-Metric – P-metric size tires are those with the “P” at the beginning of the tire size, such as P206 / 60R15. Its load capacity is based on an engineering formula that takes into account its physical size and the amount of air pressure.
European Metric – Euro-metric and P-metric tires of the same size, such as P206 / 60R15 and 206 / 60R15, are equivalent in their dimensions with only slight differences in their load capacity and inflation pressure. They are interchangeable if used in pairs of shafts or sets of four.
LT-Metric-LT-metric tires are equivalent to P-Metric tires, but have slight changes in load capacity. Many 1/4 ton and 1/2 ton vehicles use Euro-metric and P-metric size tires, while 3/4 and 1-ton vehicles use LT metric size tires.
High Flotation Light Truck – Designates tires with a lower aspect ratio and higher flotation characteristics, which provide better off-road traction. Information on these tires is always expressed in inches.
T – Temporary Spare: If the letters on the sidewall of a tire begin with a “T”, it means that it is a Temporary Spare designed to be used only for a limited time until a flat tire can be repaired or replaced.
The set of numbers and letters on the side of your tire, 206 / 60R15 for example, can provide you with a wealth of information. The first number represents the width of the section or the width of the tire. This is the distance between the outer sides of the tire’s sidewalls, measured in millimeters or inches on a high-flotation tire.
The next number is the aspect ratio. This is the ratio of the section height of the tires, which is the distance from the seat of the rim to the outside of the tread, and the width of the section. The aspect ratio is generally expressed in increments of 5, such as 60, 70 and 75. Therefore, on a 206/60/15 tire, the aspect ratio is 60% of the section width.
Another piece of information is the type of tire. There are two basic types of tires:
* R-Radial: A radial tire is one with support belts, usually made of steel, that run radially around the tire. * B – Bias: A bias tire (or cross ply tire) is one with ply that runs diagonally from bead to bead. One layer is laid skew in one direction, and then successive layers are alternately laid in opposite directions and intersect each other.
The final number in the size of a tire is the diameter of the rim. Tires that have a rim diameter in inches are the most common type used. Tires and wheels that have a half-inch rim diameter (14.5, 15.5, 17.5, and 19.5) are used on some heavy-duty flatbed trailers, trucks, and vans.
You can also find important information about your tires by referring to the Unified Tire Quality Classification (UTQG) letters UTQG. The (UTQG) system measures three things:
Footwear (520)
This rating indicates the relative durability of a tire, based on standard government testing after approximately 7,000 miles of driving on a controlled test circuit. The general rule of thumb is that you can add two zeros to the number to estimate the average life you can expect to get from the tire under normal driving conditions.
Traction (A)
This rating is based on government testing to measure the ability of a tire to stop a car moving in a straight line, on both concrete and asphalt surfaces. Tires are assigned traction grades AA, A, B, or C, with AA being the highest.
Temperature (A)
Temperature rating indicates the relative ability of a tire to withstand harsh operating conditions. Tires are assigned temperature grades of A, B or C based on testing, with A being the highest.
The DOT number on the sidewall of your tire also includes important information.
* The first two characters designate the tire manufacturer and the plant code.
* Characters three and four indicate the size of the tire.
* The fifth, sixth, seventh and eighth characters (optional) identify the brand and other characteristics important to the manufacturer.
* The last four numbers indicate the date the tire was manufactured.
The information in the tire’s Service Description is the tire’s load index and speed rating. The load index is an important number with respect to the trailer or transport. Load index numbers range from 75 (852 pound load capacity per tire) to 125 (3,638 pounds per tire). The speed rating indicates how the tire is rated for its ability to operate at high speeds as tested by the US government and is represented by the letters Q through Z. In general, a higher speed rating will give as a result better overall handling.
Remember, your tires are your only connection between you and the road. Now that you know the language of tires, remember to treat them well.