patinum

I'm considering going with a non-stagger setup for autox (275 A6 all around, Comptech bar on full stiff, 2*f/2.5*r camber, undecided toe). Because of this, I don't want my car to understeer too much when I'm on street tires (on oem AP2 wheels). I was thinking that I'd like to go 255 all around or 275 all around. Is this too much? Is there a reason 275 in front is acceptable for autox, but not acceptable for street? I may do a redline time attack event on street tires as well (street class), so that is why I am looking at 275.

Tires I'm looking at - Kuhmo XS, Driezza Star Spec, Nitto NT05.

John Grant

A-X guys use a much different setup than a time attack car will! there are other ways to cure under steer than going to a huge tire that could actually slow you down. remember that you have to accelerate, and stop your tire and wheel. your tire is a huge friction surface and having too much for the car will actually slow you down around the track. heavier wheels and tires will also add to unsprung weight which you strive to get rid of on a track car. When it comes time to set your car up for the track, take small steps. Drive it and make changes towards making it faster, then you and your car will progressively get faster.

CKit

I wonder if a non-staggered autocross setup might be a good staggered street tire setup (with regard to bars and alignment)?

I could see wanting a little bit more "turn in" on an autocross course than on a track... maybe having 275s all around for AX and 255/275 for track? Obviously, it would be a compromise by definition... but maybe better than 275s around for track?

patinum

That could be a good idea. 255's should fit okay on AP2 fronts right?

I guess my big concern is that if/when I set up the car for neutral steer for autox, I'm going to end up plowing every turn on the street given the stagger ratio change. Not that I drive aggressively on the street, but having an S2000 for 4 years has me fearing understeer more than oversteer.

CKit

I don't think it would matter very much for normal street driving.

You could always soften your front bar a notch or two on the staggered street setup.

Burgman

Street tires have a softer sidwall than a race tires so 255s on the front probably will not work or fit on stock wheels. Most tire manufacturers do not recommend a wheel that narrow for 255s.

On a side note. I am running 225 Dunlop Star Specs on the stock front wheels and they are about as wide as the stock 245 rear tires.

alvanderp

Hoosier A6's have significantly stiffer sidewalls than any street tire you can get. The transient response of even the High-Po streets you mention would be absolutely horrible with a 275 pinched on a 7" wheel. It would be like driving on a wet noodle.

Clark

Patinum,

I totally hear you about not wanting a plowing S2k. I don't AutoX, but there are a couple of looooong corners at a couple of tracks I drive where I experience nothing but understeer, and I HATE it.

My question is your experience (in any form) of putting such a wide tire (255 or 275) on such a narrow tire as stock. Doesn't that 'pinch' the tire too much and compromise the sidewall stiffness?

Yes, I am thinking of those Ultrlagerra's and how wide I can go.

patinum

Thanks. This is the answer I was looking for. It seemed odd to me that people are stuffing 275 A6's on a 7" wide wheel while others were saying you should go above 245 on a street tire. I figured it had to be something like this or the racers vs drivers dilemma.

Orthonormal

Don't worry too much about a staggered street tire setup understeering more than a non-staggered race tire setup. Since street tires have less grip, they are more prone to power-on oversteer, so the wider rear tires will help the rear end stay stuck in a turn where you're accelerating.