Forward Traction

[NOT A TA]

ET streets are bias ply DOT legal drag tires. They will not work well for road course activities. I use them for Drags and around town with 3.73 rear. I have the Yokohama 17's for road course open track and high speed events as well as highway driving and use a 2.72 or 2.41 rear with them. I decided I couldn't have my cake and eat it so I have a couple setups to choose from. I sold my 255's after deciding they would be a comprimise for the varied events I like to attend. I've nener tried the Sportsman SRs.

John

[TnBlkC230WZ]

Maintaining two sets of tires is doable, but swaping rear gears would be a pain. I wouldn't mind having 2.72s for cruising.

[DarkoNova]

It's mainly because of the sidewall (or lack thereof). Well, aside from the actual compound and tread pattern. The tall sidewall of a typical 15" wheel helps flex a bit under straight line acceleration. Low profile tires have next to nothing for a sidewall, so they transmit the turning motion instantly. The lack of much sidewall is good for handling, though, as it creates a stiffer tire that doesn't flex. There was a video a while back that had a funny car launching, but it was in slow motion, and you could see the tire wrap up. Pretty neat.

Matt

[TnBlkC230WZ]

I've seen images of wrinkle wall tire flex. It's pretty neat to watch. I guess it is storing the energy to be released further down the track when it can be used.

[Boesch]

It's mainly because of the sidewall (or lack thereof). Well, aside from the actual compound and tread pattern. The tall sidewall of a typical 15" wheel helps flex a bit under straight line acceleration. Low profile tires have next to nothing for a sidewall, so they transmit the turning motion instantly. The lack of much sidewall is good for handling, though, as it creates a stiffer tire that doesn't flex. There was a video a while back that had a funny car launching, but it was in slow motion, and you could see the tire wrap up. Pretty neat.

Matt

This is a great explanation and Matt has hit the nail on the head. This is the exact reason that all top fuel dragsters run such small diameter wheels on the back. Take a look at how much side wall flex there are on those tires, you can see it as they sit at the line. That's just the same difference you'll see with low profile tires and 15" tires, just magnified.

So from an engineering standpoint this means that you have a slightly delayed reaction between the axle twisting and the tire rotating on the ground. This leaves enough time for the tire to start rotating just a tad slower which helps it to maintain traction. Without the delay the tire accelerates so fast that it can not maintain traction. I think we all understand how fast you get going when you're spinning.