Car Tires: Buying the Right Car Tires

Found on carrepairbeat.com

By Justin Cupler

Contributing Writer February 28th, 2011

Buying car tires is typically a confusing and costly endeavor. There are so many numbers, ratings and warranties to take into consideration and they can all make your head spin. We will outline the basics of getting the right tires for your car.

Tire Size

Car tires are always sized in the format PXXX/XXRXX, with the “X” being a variable number (i.e. P225/60R16). This is the most important part of the tire, as it sis sized to both fit your rim and to keep the speedometer accurate. For every change in overall tire circumference, you can anticipate a small change in speedometer accuracy.

The proper tire size for your vehicle is located on the vehicle information placard inside the door jamb.

Speed Rating

After the tire size you will notice a single letter, this is the tires speed rating. This basically means the maximum speed that the tire can handle before failure occurs, the typical ratings you will see are: S, T, H, V, W, Y, and Z. “S” is the lowest rating, “Y” is the highest rating.

Using the proper speed rating for your vehicle is imperative to your safety, even if you are not a “racer.” The proper speed rating is located on the vehicle information placard. You can use a higher speed rated tire, but never use a lower rated tire.

Load Index/Rating

The load rating is used only on truck and SUV tires and indicates the ply of a tire and its highest capacity. It is indicated by a letter, the common letters to see are: C, D, E and Q.

The load index is used on passenger tires, and is a set of numbers right after the tire size and before the speed rating. They are typically between 90 and 100, and the higher the number, the more weight each tire can bear.

The proper load index/rating is found on the vehicle information placard and you must always use at least the rating recommended, you can use a higher rated tire.

Treadwear

Treadwear is a commonly misunderstood rating. This rating is a relative rating, meaning it is relative to the treadwear numbers below and above it. For example, a 400 treadwear tire should last twice as long as a 200 treadwear tire and a 200 treadwear tire should last twice as long as a 100 treadwear tire.

This rating is not regulated by the U.S. DOT, so it is not guaranteed accurate.