JackOlsen

This isn't a question about my car, but about cantilevered slicks in general. As I understand it, cantilevered slicks do two things. One is to increase the width of tire you can run on a given rim by having the sidewall deliberately bulge out (while remaining stiff) to an extended width. They also have some amount of camber 'built in' to the tire, which I take to mean one sidewall is higher than the other.

Is this true?

If so, do you mount the larger diameter side in, or out?

My guess is that this is wrong:

kurt M

My guess is yes, you are right that you are wrong. If one side wall of a tire were bigger in dia than the other the tire would roll in a circle. If you forced it to go straight it would scrub one side or the other and overheat. Tilting a cylinder, that is setting some camber, is different than rolling a truncated cone. I guess you could make a tire stiff enough that the smaller side would not contact the surface unless loadded up. Even then there would still be some scrub that would make heat and rob power.

Stagger comes to mind but that is running different dia tires from side to side to make up for driving around in a circle over and over.

analogmike

They ACT like they have camber built in, i.e. you don't need to run more than about a degree of negative camber for best performance. But they are symmetrical, you can mount them any way and even flip them after you wear out one side. I have a set mounted up for my RS on 7 x 15s and they are pretty good for autox but I am wearing out the inside edges due to my radial tire camber settings.

fatbillybob

What is the difference between a cantilevered slick and just putting a slick that is larger than specified for your particular wheel, i.e. going one size too large?

T.Asay44

Yep, we run cantilevered slicks on our Sprite and this is what we do to get the most out of them. Of course they have a few too many heat cycles on them by this time to be fast, but hey that's what you have to do on a budget!

JackOlsen

Thanks, guys. I haven't seen one in person -- only in a few pictures -- and it looks like the person describing the tire to me had it wrong.

So as I now understand it, the key construction element to the cantilevered tire is that it allows a wider on a narrower rim because of a flaring sidewall. But there's no built-in difference in sidewall height.

analogmike

The cantilever tires are built totally different than a normal tire. If yousee one unmounted, it looks odd as the sidewall is round. You can't fit a 9" wide cantilever tire on a 9" rim, it's designed for a 7" rim and you can't pry the beads that far apart. I guess they were designed to take advantage of SCCA racing classes that only allowed 7" wide rims.

Here is what they look like on my '73:

fatbillybob

Wow. you learn something new everyday. I have never heard of these or seen these. I also have never seen say a goodyear G19 slick "cantilever" say in a BobWoodman website or elsewhere.

Larry Herman

IIRC cantilever slicks were/are big in small bore formula racing, like Formula Vee, where they mandated very narrow rims, but had no restrictions on tire width.

Bill L Seifert

Cantilever slicks have been around since I started racing in the early 80's, probably longer. For you NA 944 runners, Avon's new DOT race tire, the Tech Ra (Advanced) is slightly cantilevered. A friend of mine has been using them since last summer. His size is 225-45-15, and they are 1/2 inch wider than my Hoosier 225-45-15's because of being slightly cantilevered. I am sure they come in 225-50-16, 225-45-17, and 275-40-17, maybe more sizes, I didn't ask.

My friend and I are equal on some tracks, and he beat me that day with the Avons and Hoosiers, but then again, my Hoosiers, were pretty well shot, and his Avons were almost new. Too many variables to know for sure, but he swears by the new Avons.

Bill Seifert

1987 944S Race Car