Rick Robinson: Hi! I'm Rick from Springfield Motorsport, and we're here today to talk about selection of custom wheels and tires for your car. In this segment, we're going to talk about tire selection. Once again, use of the vehicle is the most important factor to start with and selecting the right tire. This is going to be a daily driver or you're going to be driving in all kinds of whether and you really want to stay with an all-season tire as opposed to going with the high-performance tire that typically uses a rubber compound, that doesn't do well particularly in icy, snowy conditions, and often don't do well in the rain as well. Or again are you going to be campaigning this car on a dragstrip and you're really want and all our performance tire that gives you maximum grip. First thing to consider when selecting your tire. So first of all let's talk about how the size of the tire is described in the first place. You'll notice on the side of the tire is printed 245/40ZR20. The 245 is the width of the tread on the tire. It's not the overall width of the tire itself but it's the width of the tread and it's in millimeters. So this particular tire 245 millimeters wide at the tread.
The second parameter 40 is called aspect ratio, and we'll come back to that point. The third parameter is the 20, which is the overall diameter of the bead of the tire which has to match of course the diameter of the wheel that you chose. So this particular tire is a 20 inch tire. Now the aspect ratio, this is the parameter that's often confusing to people. It's not an actual dimension. It is the ratio of the height of the sidewall of the tire to the width of the tire.
So on this particular tire, being a 245 millimeter tire, the sidewall height is 40% of the width of the tire. That's what the 40 stands for. So this particular tire is 98 millimeters high on the sidewall height and as we discussed in the earlier clip, that's a very important factor in the performance of the tire. More sidewall height, more flex, more grip. Narrower sidewall height, better look, but less grip from the tire. Now the last parameter we'll mention, is the letters that are in the tire, rating on every tire. In this particular one, it's a ZR rated tire. The Z is an indication of the speed capability of the tire. In this particular case, this one is capable of speeds in access of 150 miles an hour. Again important thing, how you're going to use the car and how you're going to use this tire in the kind of performance that you expect out of this tire.
Now the last parameter consider in selection of your tire, is the tread pattern and the tread compound of the tire itself. A wider or more open tread pattern is going to shade water better, it's going to perform better in wet conditions. A slick tire is going to give you a better grip because you get more rubber contacting the road, but it's not going to do well at all on the wet road. Softer compounds have better grip but higher tire ware, a harder compound is going to give you more durability, but again is not going to give it the same traction that other compounds will.
So consider how you're going to use the car, the kind of driving conditions that you going to be in, and study this carefully before you make that selection. So now that we've talked about all of this factors, that you have to consider in the selection of the proper wheel and tire for your car. In the next session, we'll talk about installation.