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Everything That You Wanted To Know About Tires for Cars Trucks and SUVs

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Created on: 2012-11-30

Tires have tons of information on their sidewalls, if you know how to read them. Watch this video to learn what it all means!

Hey, I'm Jeremy from 1A Auto. This is a tire. Today I'm going to teach you about what all the numbers and letters on the side mean.

One of the cool things about tires is that the side of the tire actually tells you everything about the tire. One of the things that I find really interesting is that the tire actually tells you how old it is. It tells you the month it was made and the year it was made. This is really useful if you're buying a used set of tires from a junkyard or Craig's List or eBay or something like that. Even if you're just buying them brand new at a store you can find out how old the tire actually is, because sometimes you buy a brand new tire but you find out the tire is actually a couple of years old. You always got to watch out for that at any place that you're getting a really good deal on tires. It may be an old tire.

The way that you figure this out is, on the side of the tire, there's an oval with some numbers in it. If the tire was made before the year 2000, it's a three-digit number. It'll be the week of the year that it was made and then the year that it was made. In this case it would be the 16th week of the seventh year. This could actually mean 1987 or 1997. In 2000, the number was actually standardized because tires were getting confused between decades. Tire manufacturers started using four-digit codes. Now it's the 16th week of the seventh year and you can tell it's 2007. There's no longer any confusion of 1987 or '97. It's 2007 because it's 07. This is, again, really useful if you're buying a used set of tires. I've used it a bunch of times and I've often been shocked at what I've found.

On an actual tire you can see the number right here. You can see it says 1607. If this was made in 2009, it would say the week it was made, in this case 16, and then it would say 09 instead of 07. If it was a different week of the year, it could say maybe 32 of 07. It's always the first two digits are the week and the second two digits are the year.

One of the most important things about a tire is the tire size. In this case we have 235/45/17. Two-thirty-five is the amount of millimeters wide the tire is. The more millimeters, the wider the tire. The less millimeters, the thinner the tire. Forty-five is the height of the sidewall. In this case it's 45 percent of 235. This is always a percentage of the width. Seventeen is the diameter of the wheel itself. In this case it's a 17-inch wheel. We have a 235 wide; 45 percent of 235 is the height of the sidewall on a 17-inch wheel.

On the tire itself, you can see the size of the tire right here: 235 millimeters; 45 percent of 235 is the height of the sidewall. R actually stands for radial; it's a radial tire. Pretty much all tires these days are radials, and 17 is the diameter of the wheel. So: 235/45/R/17.

Another really important factor about tires is the load rating, the speed rating and the type of tire that it is. Today we have a 94Q M+S. That's what the side of the tire says. Ninety-four is the load rating. That means it can handle 1,477 pounds all on that one tire. You multiply that times four and hopefully your car weighs less than that. If it weighs more than that, you're overloading your tires and it's unsafe. Q is the speed rating. That means these tires can go 100 miles an hour safely. The higher the letter, the faster that you can go. You'll see something like a Corvette might have a Z-rated tire on it. Obviously this is pretty important if you ever take your car to the racetrack or anything like that. You want to make sure your tires are safe to go the speed that you're going to be going. M and S. That is mud and snow. That's what most tires are. If you go look at your car right now, it probably has an M and S on the side of it. It's pretty much a good all season tire. You can buy strictly winter tires or strictly summer tires or strictly race tires, but M and S is the pretty standard all season tire.

Right here next to the tire size, you get your 235/45/R/17, you can see there's an 94QM+S. That's the 94 load rating of 1,477 pounds. The Q is the speed rating of 100 miles an hour and then mud and snow. It's basically an all season tire.

On the side of the tire, you'll find a max inflation pressure. This is not what you set your tire pressures to. This is the maximum amount of pressure that the tire can handle without exploding or at least becoming dangerous. In our case, it has a max inflation pressure of 44 PSI. That's actually what a lot of tires are. Once again, that is not what you set your tires to. That is the maximum that they can handle as far as pressure goes. You always want to follow the instructions on your door. In the doorjamb, it usually says the recommended tire pressure for your car. Every car is different. It's usually between 28 PSI and 36 PSI, sometimes higher, sometimes lower. Heavy trucks have very different tire pressures, so you always want to be careful with those, the same with trailers. Those have very different tire pressures as well. Once again, the max tire pressure is not something that you want to put in your tire. It's just the maximum that the tire can handle.

Right here you'll see the max inflation pressure of 44 PSI. Once again, that's not what you want to inflate your tires to. That is just the maximum pressure that tire can handle before it gets dangerous.

The last thing worth mentioning, as far as tires go, is the sidewall of the tire. The sidewall right here is this 45 number as you can see. It's also the most important part of a run-flat tire. If you have one of the newer cars that has run-flat tires, this section of the tire is actually thicker. It allows it to be driven while flat. Even though there's no air pressure in it, you can still drive it to the nearest gas station or a shop to get it repaired or at least put some air in it. A normal tire, like this one, as soon as it gets flat, the sidewall actually compresses and the sidewall will actually start breaking up as you're driving. Eventually the tread separates from the bead and the tire will come off the rim and then you destroy your wheel. Obviously that's not the best situation.

One last thing worth mentioning about tires, today, is the different sections of the tire. This inside section right here, this is the bead of the tire. Within this is actually a metal cable. That holds the tire tight against the rim. A really common problem with aluminum wheels is corrosion builds up on the inside of the aluminum wheels and it actually creates a gap between this rubber seal and the wheel. Air will leak out and eventually your tire will be flat.

That's about it for tires today. Hopefully you learned something. If nothing else, you can go outside and see how old your tires are.

Once again, don't forget to visit 1AAuto.com. Thanks for watching.

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