Tire Types and Markings

Size, shape, materials, and construction are all factors that will govern tires' longevity as well as the ride they furnish. The first and most important rule in choosing tires is to follow the directions and recommendations in the owner's manual. Check out the information embossed on the sidewall as well. This information can help the owner choose a set of tires that will suit both the car and the driver's personal needs. The markings on a tire will give the weight (load), size designation, serial number, tire type, carcass cords, DOT, and profile size. Other markings on the tire will probably be the brand name and the name of the tire. The "size designation" is a combination of one letter and four numbers and is a three-part code. The letter denotes the sidewall-to-sidewall width of the tire; the two numbers grouped with the letter refer to the height-to-width ratio; and the numbers following the dash indicate in inches the diameter of the wheel rim the tire will fit. To replace the tire, the own will find the sizes that will fit the car specified in the owner's manual. As to "tire type," government regulations require that every passenger tire be stamped either "tubeless" or "tube-type," but more than 90%% of the passenger cars are tubeless. "Belted" would indicate that a tire has extra strength in its construction. In addition, if the tire were a radial, it would be designated as such - a necessary precaution because radials should not be mixed with other tire types except when the radials are used as the pair on the rear axle.