Tire Sizes

Do you find it difficult to find out the tire sizes needed for your vehicle? Are you like me? Do car terms sound like go over your head like a foreign language? When someone says “pump” do you think of that thing in the back of your grandfather’s ranch that they crank to get water from the well? They don’t put those in cars, do they? Let me tell you, it’s taken a bit of time, but I’m slowly learning different parts of the car, like interior, engine, tire and tie sizes speak. I found that learning even just a little bit of automotive sector has been not only helped me find the right parts for my car, but it’s helped me save a little money along the way.

Understanding the tire specifications

Take tires for example. When I’m ready to buy my next set of tires, one of the first things I do is look at the tire sizes I already have. There, on the side, is some gibberish about tire sizes, psi, and other things. Not knowing what any of it meant, I just went to the store and looked for a tire with matching gibberish. At least that way I had a sense that I was buying pretty much the same thing that was already on my car. Makes sense, right? Or does it? Truth is that when it comes to tires, you have a lot of options to choose from, and it is possible to put the wrong set on your car. It’s up to you to choose the right tire sizes for your needs, and understanding even just a little bit about the tire sizes and other tire specifications can go a long way to helping you make the best choice.

Writing on the wall!!

The average gibberish on the side of your tire will look something like “p175/50R 14 80z”. Uh huh, right. I got it. That’s the play where the quarterback fakes a pass then hands off to the running back, right? Not quite. That little bundle of letters actually packs a lot of information that will help you get the right tire sizes with appropriate other parameters for your vehicle and possibly save some money along the way.

The code break down

Here’s how the language breaks down, the first letter tells you the kind of vehicle that the tire is meant for. In our example, the “P” stands for passenger vehicle. Therefore, if you’re shopping for a truck tire, this isn’t the one for you. A truck tire will have an “LT” for light trucks. A “T” designation is for temporary or spare tires. That number 175 next to the “P” tells you how wide the tire is. In our example, the tire sizes are expressed in millimeter width.

That letter “R” after the 50 tells us what kind of tire we have. In this case, “R” stands for radial. There can be ‘B’ or ‘D’ letter present instead of ‘R’. While “B” stands for bias construction, “D” denotes diagonal bias construction. Just after R, (in our example) can you see the number 14? Well it denotes the size of the rim diameter for the wheels of your car. Your tire sizes can be determined with this significant factor.

After this we have a number that tells you how much the tire can carry. In our example, that number is 80. When we look at the maximum load-carrying capacity chart we’ll find out how much weight four of these tires can safely accommodate.

This is starting to seem less and less like gibberish now, isn’t’ it? That last little letter, in our case a “z”, is what is called the speed rating (how come mine doesn’t say “fast”?). Actually, ours is rated pretty high. A “z” rating means that the tire is capable of handling speeds up to over 150 miles per hour. That’s what I’m talkin’ about! Other ratings you might find include “s” which is a rating for upto 112 mph, “h” for up to 130 mhp, and “v” for up to 150 mph.

As crazy as it sounds (to some) you really shouldn’t drive faster than the speed rating for your tires. As your speed increases, so does friction. Friction causes the tires to heat up. When tires get overheated they start to fall apart. Having a tread come unglued from the tire is never a good thing. Speed ratings are there to help you keep safe.

I hope that you’ve picked up at least enough knowledge to know that while the stuff on the side of your tires won’t unlock the secrets of the universe, it will help you determine what you already have, and what you can look for in your next tire.

This same information about tire sizes and its other related parameters is also available on the identification sticker found on your driver’s side door jam, or in your vehicle’s owner’s manual.