What do all those letters on your tires stand for?
Ever notice that your tire is covered with writing? It's like some hieroglyphic art form. Of course, you know that it's not just graffiti, but to most of us, it might as well be. Would you like to know what all those codes on your tire mean? It won't lead you to buried treasure, but it could help you make a better tire purchase.
Prominently featured on your tire is a set of numbers and letters that looks something like this: 225 70 R 16 91 S.
The first number 225, is the width of the tire in millimeters, or the width between the sidewalls of the tire when it is fully inflated and not carrying a load. When you replace tires, you need to match this width number, or the tires won't fit properly in the wheel wells.
The 70 is the aspect ratio of the tire, which is measured by taking the height of the sidewalls and dividing it by the tread width. If you drive off-road, it should have a high aspect ratio. For high performance on the road, you want a lower aspect ratio.
The R simply means this is a radial tire.
The 16 represents the Diameter of your Rims
The 91 is the load rating index, or in other words, a rating of how much load a tire can safely carry. If you frequently haul heavy loads, you will want a tire with a high load rating.
The last letter in our “code” sequence, the S, is the speed rating on the tire. Not all tires have this rating. In general, the closer the letter is to the end of the alphabet, the higher the speed rating. In other words, Z is the highest rating and A is the lowest. One exception: H comes between U and V. Why? Your guess is as good as mine.
If you ignore all of the markings on your tire, that's okay. When you need to replace your tires just ask your friendly and knowledgeable Auto Select tire professional for his or her auto advice on the best tires for you and your vehicle. Replacing tires is a standard part of preventive maintenance. We all have to do it sooner or later. And the better we understand what we're buying, the better our vehicle will perform and the safer we will be on Wisconsin roads. Good car care is informed car care.