Tire Numbers Explained

Buying tires is not something we have to do often, at least we hope not, so when we do it can be quite confusing. I have been driving for many years and only recently did I have to buy my first set of new tires. I have never had any problems with tires other than the occasional flat and I really do not drive enough miles nor live in an area with harsh Winter driving conditions so I suppose I owe my inexperience with buying new tires to sheer luck. In any case, my first foray into purchasing a new set of tires was a bit overwhelming at first. I had no idea what I was getting into, but when I saw all of the options, the different types of tires, so many tire brands and the wide variation in pricing, I knew I was going to have to do my homework. The first thing I did was learn how to read the tire markings on the sidewalls of my existing tires. I thought I might share what I learned in the hope that people who find themselves shopping for new tires for the first time might find it useful.

When you need to replace the tires on your car a good place to start is checking to find out what type of tires the manufacturer installed on the vehicle. The sidewall of your current tire will provide all the information you need. On the tire you will find the tire width, aspect ratio, tire type, wheel diameter, load index and speed rating. If you understand all the numbers and codes you can make a much more informed decision about what you need.

The first number stamped on the sidewall is the tire width. It is extremely important that you match the width which is described with a code like P225. Next is the Aspect Ratio which measures the ratio of the height of the tire to the width. The third code refers to the type of tire, for example R for radial. The next number refers to the rim size on your vehicle and that is followed by the load index. The load index refers to the amount of weight the tire can carry; you will want a number equal to or higher than what you currently have. The next letter will refer to the speed rating. The speed rating refers to how the tire can handle high speeds; it ranges from a low rating of A to a high rating of Z. You want a rating at least as high as the manufacturer's rating.

If all of these ratings seem confusing, your tire dealer can help you. For the basic passenger car on the road today, an all weather tire that meets the minimum manufacturer's ratings will serve you very well. If you drive a BMW or other luxury car you will want to consider upgrading to a performance touring tire which offers better handling. There are also high performance sport tires that are made just for sports cars like the Dodge Viper that will corner better and handle higher rates of speed.

The most important factors to consider in picking a tire are the conditions that you drive in and how you drive. If you live in the north where snow and ice are a frequent concern then you will want to choose a winter tire but if you live in the south a touring tire will offer better performance.

Buying tires based on price could wind up being a bad idea as your tires are one of the most important safety features of your car. You should still compare prices, look for tires on sale, and try to get the best price on the right tires. Knowing what the numbers on the side of your tires mean is a good first step and should get you pointed toward buying the right tires for your car and situation.