Car Tech 101​: How tires work

[MUSIC] Now I could do half an hour on this subject alone and put us all to sleep. But instead, I want to touch on four high points about tires that I think you can keep on your mind Kind as you go shopping for them. First thing to know is the big concept, which is your tire isn't this big blob of rubber. There's a lot of engineering going in here, a structure that is built to operate a certain way, not just hold air. And unlike just about any other part of your car, this one changes shape rather dramatically when it's working. That's an amazing thing Thing to keep in mind, as well. [MUSIC] Now, the first concept is the contact patch, or the footprint. That's where this tread here sits and meets the asphalt, and it varies in width and length, if you will, kind of this way, depending on the tire design, pressure, and your car's weight. What happens at the contact patch is amazing. That footprint allows three major things to happen, first of all for power to be applied to the road as the wheel is turning one way in relation to the car and for braking to happen as the wheel is being resisted, kind of in the opposite rotating direction in relation to the car. [MUSIC] And then you've got the other two axis which is kind of out and in, laterally across the tire. That's how cornering happens and you get that nice grip. And all of those dynamics typically will happen all at once or within a Second of each other and the tire has got to be able to deal with all of them well. [MUSIC] The next thing that we all notice very much, and you should be aware of, is the profile of the tire. It's height with relation to it's width. Now we love our low profile tires, they look great on almost any kind of car. It's been a big trend the last few decades to get this sidewall lower in relation to the width of this tread. But what does that is the frame inside the tire. They're called the belts. They're made of either polyester or steel, and they don't just bring that profile down, when you do that you [MUSIC] You change the nature of how the tire operates in two kinds of loads. One is radial loads. The load that comes if you will, kind of vertically down on the tread. The steeper this is, that will change the ride comfort. You get more drumming in the car, you get less of a soft Compliant ride. And this low-profile tire also has a very different behavior for lateral load, which is sort of this side to side load. Think of it as a cornering load, for the most part. This low-profile sidewall is stuffer, this tire is gonna, gonna skoosh less left to right as you go in and out of a corner. That's great for performance, but that can also harshen up your ride because there's less give in this overall design. It's a tradeoff. Between that sharp performance and that comfortable compliant ride quality. And then of course there's the tread itself, that actual intricate pattern that we all know and see on the face of the tire. This isn't just here as a random pattern or to look cool They gave deal tire, to be honest, has no tread if you're driving in perfect conditions on a dry piece of pavement on a summer day, like this slick right here. It puts the maximum amount of rubber on a dry, clean, smooth piece of pavement. But, that's not the real world. So our tire's on passenger cars do have tread. We drive on roads that have gravel. [MUSIC] That have snow. That have rain. So your tread is designed to deal with all those. To work it's way around gravel and find the traction between the actual rocks. To get down in snow and find some grip in that material. Or Or on a rainy day to take the water in a middle of a tread as you race down the street, and it evacuated out the side. Otherwise you end up flying on the surface of the rain, that's called hydro-planing it. That's no fun. [NOISE] And Toyota Factor's about tread design, the way that it grips and then releases the road is a key part how well this thing does in corners. [MUSIC] Is it going to create over spear or under steer, all tires have some slip as they turn, but the nature of that allows the car makers to dial in the corning behavior they want in their overall vehicle. And finally, Trent has a lot to do with quietness of attire, the way these lugs grip and release at the road requires more or less and varying kinds of sounds That's where all the road noise you hear from tires comes from, and that's a big deal on luxury cars, in a different way on sports cars. [MUSIC] The last thing I wanna bring to your attention is rolling resistance. What it takes for this tire to roll down the road very dramatically by its design. The really grippy, wide [MUSIC] Sticky tire is going to be great at cornering, accelerating and breaking, but perhaps require more energy just to keep the car moving at a sit speed, let alone to accelerate it and that's not a good guy in an era where auto makers are looking everywhere to save a few drops of gas per mile Now it used to be that low rolling resistance tires, which you'll find on many very high efficiency cars, were awful. They were like having a three day old bagel mounted on each wheel. Now they tend to be pretty decent performance tires. Not extreme, but acceptable. They're much better at having a quiet ride Pretty good performance and actually looking good as well. [MUSIC] Oh, by the way, if you want to know what all of this stuff on the side of the tire means, it calls out much of the technology within it, and we did a separate piece on this a little while ago about how to read your sidewalls. It's important for the tires you've got but especially for the ones you're considering buying. I'll put a link into our episode 64 show notes. Take you right to that piece, and that's at CNETonCars.com. [MUSIC] More car tech [INAUDIBLE] right now at CNETOnCars.com. Click on Car Tech 101. [MUSIC]