[1LE76G]

Hey guys, wondering if anyone has attempted or has some good knowledge on why or why not to run 2 different brands for autocross. Im looking at doing 305/19 RE 71Rs on the front of my 1LE and 325/19s RE 11s on the rear.

[sholzer]

Bad idea mix matching those two tires because of the difference in grip. Run the 305/30/19 71r all around

[Ryephile]

You'll have more grip with 305 RE71R's on the back than you will with any width RE11. That's why the RE11's were replaced by the RE71R's.

[Mr. Wyndham]

Originally Posted by 1LE76G

Hey guys, wondering if anyone has attempted or has some good knowledge on why or why not to run 2 different brands for autocross. Im looking at doing 305/19 RE 71Rs on the front of my 1LE and 325/19s RE 11s on the rear.

Never a good idea to mix and match tires unless you're drag racing with slicks.

What are you hoping to achieve?

[1LE76G]

Originally Posted by Mr. Wyndham

Never a good idea to mix and match tires unless you're drag racing with slicks.

What are you hoping to achieve?

Id like to solve my understeer problem, past 2 auto crosses I have had a good amount of push. After inspecting my tires today it seems I've wore the outsides on all 4 of the tires, so I'm unsure if thats normal for this car or if I am lacking negative camber.

Originally Posted by sholzer

Bad idea mix matching those two tires because of the difference in grip. Run the 305/30/19 71r all around

Ok this is what i was wondering. 305s were my original plan, but saw these 325 re11s and were pretty tempted

[ZL1 1LE]

I’ve had both and the RE71Rs are head and shoulders above the RE11s. I wouldn’t do it just based on size.

[Mr. Wyndham]

Originally Posted by 1LE76G

Id like to solve my understeer problem, past 2 auto crosses I have had a good amount of push. After inspecting my tires today it seems I've wore the outsides on all 4 of the tires, so I'm unsure if thats normal for this car or if I am lacking negative camber.

Sounds like you need more negative camber, and set the toe out up front just a tenth of a degree or so. If you're still pushing, look into the ZL1 1LE stab bar, or an aftermarket one that will bias the car for a hair of oversteer.

Different tires could make the car unpredictable.

[Norm Peterson]

Originally Posted by 1LE76G

Id like to solve my understeer problem

Attempting to solve an understeer problem by playing games with the basic front vs rear slip angle curves is not only risky; it can hurt you in other places (if the rear insists on being a lot looser the car can get "out of step with itself", typically in slaloms).

I've seen an extreme example of what you're suggesting . . . and it flat-out should not have been permitted to pass tech inspection.


Norm

[Ryephile]

Originally Posted by 1LE76G

Id like to solve my understeer problem, past 2 auto crosses I have had a good amount of push. After inspecting my tires today it seems I've wore the outsides on all 4 of the tires, so I'm unsure if thats normal for this car or if I am lacking negative camber....

Understeer "problem" with a 1LE? The car doesn't exactly plow, it's impressively neutral on the track.

Let's start with the obvious: what's your alignment? If you're not at a minimum at the Performance Supplement "track" alignment, then you're behind the 8-ball. Even then, tire wear on this platform is proving to be shoulder-heavy even with neutral balance.

[MoreSpeed]

I was getting outside tire wear as well, but the regular ZL1 cannot get as much negative camber as you can without non-stock components. You probably need more.

The car shouldn't plow if you are not bombing into to the corners. I also would think alignment. I had one car that I got brand new that just didn't have non-optimal configurations for racing, but had different camber, toe, etc on every wheel. It was a hot mess until I got it fixed up for racing. I wondered how they could ship it like that, but....

[bensf]

I've mixed tires once without any ill affect but would not do it as a rule. The RE11 and RE71R are probably different enough that I would not recommend it.

[mjk3888]

Originally Posted by 1LE76G

Id like to solve my understeer problem, past 2 auto crosses I have had a good amount of push. After inspecting my tires today it seems I've wore the outsides on all 4 of the tires, so I'm unsure if thats normal for this car or if I am lacking negative camber.



Ok this is what i was wondering. 305s were my original plan, but saw these 325 re11s and were pretty tempted

Experiment with pressures. No need to reinvent the wheel and change to a completely different tire. Alignment and pressures.

[apexit53]

yeah there are so many other things you can do before changing tires front to rear.

Having different tires from front to back in theory would work like youre thinking but people have tried it with little success.

I played around with tire sizes and that seemed to help me with turn in.

[dontlifttoshift]

OP, are you new to autocross?

Where does the car push? On entry, mid corner, or on exit?