[Red Bread]

Originally Posted by notime

1) I used to run my 240sx to where the tires were smooth, though without ABS eventually flat spotting and carcass appearing rather soon limited lots of road time.

If you bought a new tire and had it shaved to remove the siping (and drove only on dry roads), it would wear as well as a new tire for the limited amount of remaining tread. It's the heat cycling that a tire used all the way down to the cords that hurts the overall performance of the tire.

Originally Posted by notime

2) racing slick with their rubber compounds heat up in a way I wouldn't imagine any if few treaded road tired would or ever could, and yes on road racing track tires tread and sipes are combined for water evacuation and I would guess some mechanical traction effect.

Slicks let go with frightening unpredictability. Leaving some circumferential grooves and some siping allows for a more predictable loss of traction. Slicks are great for pros, but not very amusing to amateurs.

Originally Posted by notime

3) not sure if mostly marketing or science but when I purchased Michelin XGT's for my 240sx, after a review on Rpad & Track there was discussion that the tread block design ( new at the time ) enabled dry traction and the styrene in the compound wet traction.

Tread block design can lead to more predictable slip angles and better feedback, but siping (not circumferential grooves) is primarily for snow grip (which is why pure summer tires don't have sipes) and lateral grooves are for evacuating rain. Compound will certainly help with rain too.

Originally Posted by notime

4) Hoosier and Yokohama make partial slick tire face designs and not sure if that is enough evidence that tire wear down beyond wear bars are superior for dry traction.

DOT approved tires have to have three grooves. Even slicks tend to have a bore cut into the tread to indicate the amount of acceptable wear before replacement is needed. Think of it like an inverse tread bar.

Originally Posted by notime

5) though I can imagine wear down to around wear bar level on hot road surface may create more surface contact, better then a new tire?

Absolutely, assuming equivalent heat cycling.

Originally Posted by notime

6) tires getting shaved for track use, traction or reduce squirm and increase roundness, ( my XGT were shaved by Michelin from the factory for perfect roundness)

This can make a slight difference, but most cars weigh enough to sort this out on their own rather quickly.

Originally Posted by notime

Just some thoughts , sure a magazine had done a test on the subject somewhere. And when your having a good relationship with a car you can go through tires at a high rate that at times you run the tires to extreme wear levels)

Just continuing the thread jacking.