more grip on rear or front?

[Karim]

ok guys here's the deal, my front tires are a little more worn than my rears, i was wondering if I should rotate my tires before the next auto-x on thankgiving weekend? would it be better for me to have more grip up front or on the back? my friend anre I were cluelessly wondering the other day about the consequences of each, wouldn't less grip on back cause your tail end to slide around more and that'd be worst than just your fornt tires slipping a tad bit? any opinions for us auto-x noobies:confused:

Karim

[nxracer]

Under dry conditions more tread will actually give less grip. The reason is tread squirm, the more tread the more the tread squirms under load. With that in mind I would leave the tires with the least tread on the front. Mostly because on a front wheel drive car all the rear tires really do is keep the rear bumper off the ground.

Traction (http://www.tireconnect.com/TIRESCHOOLPAGES/traction.htm)

[Karim]

Originally posted by nxracer
Under dry conditions more tread will actually give less grip. The reason is tread squirm, the more tread the more the tread squirms under load. With that in mind I would leave the tires with the least tread on the front. Mostly because on a front wheel drive car all the rear tires really do is keep the rear bumper off the ground.

Traction (http://www.tireconnect.com/TIRESCHOOLPAGES/traction.htm)

thanks nxracer! you the man!

Karim

[00 scrub]

i have another tire question similar to this. When I rotated my seriosuly worn front tires to the rear it seemed that my car becamse far more neutral. Before rotating I had horrible understeer. How come my car did not oversteer with the balding front tires? Is it because the compund was getting worn down and jsut not gripping much? There was more contact patch on the fronts.

[nxracer]

You could have cooked the tires

[00 scrub]

when you mean "cooked" do you mean that i put them through too much heat by using them too hard over a short period of time? Like driving fast or doing mountain runs(well one really long 300 miles run?)
thanks

[nxracer]

Spinning the tires generates lots of heat, too many heat cycles degrade the rubber compound. I hear the GT-S tends to wear down the middle of the "stock" tire. If your pressures are right this (IMHO) points to the evil spinning tire at the cam switch over. The Bridgestone RE-92's on my GT have worn very well, except for the inner edges that is but still the car has 38000+ miles on it. The stones come off Friday and a "free" set of BFGoodrich HR4's go on, I just hope they handle as well as the RE-92's

[pitcrew]

My miata came with 92's, if you like them, you'll LUV just about anything else softer than Remingtons! we spent our first AX season on them, not knowing any better... When they finally wore out I replaced them with RE71's for the street, made it an all new car. I wish the 71's were still available. I'll probably look at Falkens when these or the Celica's need replacing.

[nxracer]

I had RE-71's on my NX2000 and in my opinion they are/were the best autocross "street tire" made. The top two cars in STS at nationals were on RE-71's not Falkens. It just plain sucks that they don't make then anymore, their replacement is nowhere near as good.

My problem is I live in Chicago and RE-71's suck in the snow so I look for a decent handling all-season tire. I know there really is no such thing as a all-season tire I'll buy into the myth anyway. Given a choice I would have got a set of Pilots but I won this award and part of it is a set of BFGoodrich tires. Any tire as long as it says BFGoodrich on the side.

They only have to get me to and from work and events anyway, Hoosier does the hard work.

[SlopeSurfer]

Originally posted by nxracer
Under dry conditions more tread will actually give less grip. The reason is tread squirm, the more tread the more the tread squirms under load. With that in mind I would leave the tires with the least tread on the front. Mostly because on a front wheel drive car all the rear tires really do is keep the rear bumper off the ground.

But is that the case with worn tires that are 'supposed' to have tread? I thought a treaded tire that had worn down was slippery cuz it wasn't made to run on that exposed rubber, guess it depends on how worn it is.

[00 scrub]

nxracer when u mean the evil cam switch-over do you mean shirping the 1-2 shift? And yes you are right my stock GT-S tires are wearing heavily in the middle.

[nxracer]

evil cam switch-over = wheel spin caused by the 40 horsepower jump at 6000 rpm

The problem is that without the a limited slip it becomes very hard to modulate the throttle and avoid the wheel spin. I would hope that with practice this could be avoided. I feel for you guys (I really do), it's hard enough to keep my wheel for spinning on a GT.

[pitcrew]

Originally posted by nxracer
evil cam switch-over = wheel spin caused by the 40 horsepower jump at 6000 rpm

The problem is that without the a limited slip it becomes very hard to modulate the throttle and avoid the wheel spin. I would hope that with practice this could be avoided. I feel for you guys (I really do), it's hard enough to keep my wheel for spinning on a GT.
Agreed! I just can't understand why Toyota didn't equip/ offer an LSD, at least in the GTS, and especially in the Spyder???? If DRIVER wasn't running her GT in stock class, that's one of the first things I'd add. So far with her car it's most noticable at a pivot cone. (We equiped her car with Konis immediately, I'd expect it's much worse with stock shocks)

[nxracer]

Actually I hear if the Koni's are set too stiff it may be a little worse than stock.

Anyway on a GT it is manageable, the trick is learning the squeeze. Last year I ran on a lot of "sealed" asphalt lots and got quite good at it. But I think it sometimes screwed me up a little on better pavement.

Jean Kinser drove a GT-S at an Evolution school last summer. We talked the next day about the car and she liked everything about it except the cam switch over. Jean is quite good at the squeeze (many years in a Neon) but the sudden burst of power was tough to handle. Had we both been smarter she would have been co-driving my car at Nationals instead of that 200SX. Given the temperature when we ran I would have covered the Hoosiers stickers and slapped on set of (her) Kumho's in a second (she is a Kumho "contract" driver). Hindsight is always 20/20.