pros and cons of staggered wheel sizes?
10-20-2005, 03:30 PM
#1
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pros and cons of staggered wheel sizes? Like on the Zo6 that runs a 17 in front and 18 in rear. what Kind of handling advantage does this create for a car? I know the GM boys didnt stagger the sizes just to confuse people... or did they? 
10-20-2005, 04:00 PM
#2
Staggered sizes could benefit handling, but not the way GM did it on the Z06. Many times rear wheel drive race cars have wider tires on the rear, because the rear tires have two jobs: holding the car in a turn, and putting power to the ground. A lower profile tire works better on the front where you want good turn in response.
The problem with having 18 inch rims on the rear is that reduces sidewall height, which is critical in making a rear wheel drive car put down power on corner exits. This is even more important on a fbody that has a solid rear axle. It would have been better to have the 17 inch rims on the back, and the 18's on the front, but have the wheel width stay the same. So 18x10.5 front and 17x10.5 rear, instead of 17x9.5 front and 18x10.5 rear. Those aren't very standard wheel sizes, and there is also the problem of finding tires to fit the wheels and car.
And of course you still have the obvious disadvantage of not being able to rotate the tires, but you can still flip them.
I run Z06 rims on the street, and the rear always breaks loose first. On the track, I run 25.5x12x16 slicks on the front and 27x13x16 slicks on the rear. All four wheels are 16x12's. This combo is very balanced and has amazing lateral traction.
For the street or DOT racing classes, I suggest just getting a set of four 17x11 ZR1 knock-off's and putting 315's on all four.
The problem with having 18 inch rims on the rear is that reduces sidewall height, which is critical in making a rear wheel drive car put down power on corner exits. This is even more important on a fbody that has a solid rear axle. It would have been better to have the 17 inch rims on the back, and the 18's on the front, but have the wheel width stay the same. So 18x10.5 front and 17x10.5 rear, instead of 17x9.5 front and 18x10.5 rear. Those aren't very standard wheel sizes, and there is also the problem of finding tires to fit the wheels and car.
And of course you still have the obvious disadvantage of not being able to rotate the tires, but you can still flip them.
I run Z06 rims on the street, and the rear always breaks loose first. On the track, I run 25.5x12x16 slicks on the front and 27x13x16 slicks on the rear. All four wheels are 16x12's. This combo is very balanced and has amazing lateral traction.
For the street or DOT racing classes, I suggest just getting a set of four 17x11 ZR1 knock-off's and putting 315's on all four.
Last edited by Cal; 10-20-2005 at 04:14 PM.
10-20-2005, 05:08 PM
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I wish it was that easy... My biggest option is 17x9.5s. anything bigger (in my price range) wont fit under the gto. Really, there is alot of suspension work that I want to do before going to the track. poly bushings, swaybars, bmr mods, etc...
whats your take on autoxing on the stock 17x8s (or possibly 18x8s) with dot competition tires?
whats your take on autoxing on the stock 17x8s (or possibly 18x8s) with dot competition tires?
10-20-2005, 07:33 PM
#5
Oh ok, I didn't notice at first you have a GTO. 17x11's and 315's will fit on a fbody with a small amount of "adjustment" but I don't know what the biggest is that will fit a GTO.
Since you are AXing, you will have to look at the rules for the class you want to race in. In stock classes, you can't use a bigger than stock wheel, but you can use any DOT race tire you want. Other classes allow bigger wheels, and in Prepared and Modified you can even run non-DOT race tires (real slicks.)
For AX, the most important mod is to upgrade the driver! If you already have a year or more of experiance racing on street tires, then get some DOT race tires. Tires make the biggest performance increase for AX than any other mod by far. The next biggest improvement is usually shocks, followed by bigger sway bars, then stiffer springs. Poly bushings don't provide enough improvement to be worth all the squeaking they do IMO.
Out of 17x8's and 18x8's, I would go with the 17's for the reasons I listed in the other post. Of course go with the widest rim allowed in your class and that will fit on the car.
Since you are AXing, you will have to look at the rules for the class you want to race in. In stock classes, you can't use a bigger than stock wheel, but you can use any DOT race tire you want. Other classes allow bigger wheels, and in Prepared and Modified you can even run non-DOT race tires (real slicks.)
For AX, the most important mod is to upgrade the driver! If you already have a year or more of experiance racing on street tires, then get some DOT race tires. Tires make the biggest performance increase for AX than any other mod by far. The next biggest improvement is usually shocks, followed by bigger sway bars, then stiffer springs. Poly bushings don't provide enough improvement to be worth all the squeaking they do IMO.
Out of 17x8's and 18x8's, I would go with the 17's for the reasons I listed in the other post. Of course go with the widest rim allowed in your class and that will fit on the car.
10-20-2005, 07:36 PM
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10% difference in circumference is about the threshold
where an F-body ABS system will pitch a fit. I don't
know how tolerant the GTO's might be. But F-bodies
with 5% sort of stagger have no trouble and 10%
range seem to get hard-braking ABS issues.
where an F-body ABS system will pitch a fit. I don't
know how tolerant the GTO's might be. But F-bodies
with 5% sort of stagger have no trouble and 10%
range seem to get hard-braking ABS issues.
10-20-2005, 07:40 PM
#7
Originally Posted by minesfaster
Will 315's fit all the way around ? IS there any modding needed to be done to the front's ?
The race tires I have are a lot bigger than 315's, and I still got them on there without too much trouble.
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10-20-2005, 07:46 PM
#8
Originally Posted by jimmyblue
10% difference in circumference is about the threshold
where an F-body ABS system will pitch a fit. I don't
know how tolerant the GTO's might be. But F-bodies
with 5% sort of stagger have no trouble and 10%
range seem to get hard-braking ABS issues.
where an F-body ABS system will pitch a fit. I don't
know how tolerant the GTO's might be. But F-bodies
with 5% sort of stagger have no trouble and 10%
range seem to get hard-braking ABS issues.
10-20-2005, 10:27 PM
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I think im going with 17x8.5 front and 17x9.5 rears, and keeping my stockers to run competition tires on...
I have ran autox before with a dropped/modded/light IROC with a t-56 and a bunch of suspension/gearing changes. Stock it handled like this car does, maybe not quite as good, modified that Iroc was a slot machine. Also, the way the car works with this IRS is alot different from the roc, seems like the IRS is more forgiving in the turns, and is definately more tunable for the track conditions. Pretty soon I am going to really dig into this gto and see what changes can be made to the rear anti-squat and how far the camber can be adjusted. the front can go almost 4 degrees negative each side
I would probably not need that much, but the adjustment IS there. I'm lucky I have a buddy with a hunter digital 4 wheel alignment machine. So I can make fine adjustments for a track day test them, and set it back to stock If I want to drive it on the street.
I have ran autox before with a dropped/modded/light IROC with a t-56 and a bunch of suspension/gearing changes. Stock it handled like this car does, maybe not quite as good, modified that Iroc was a slot machine. Also, the way the car works with this IRS is alot different from the roc, seems like the IRS is more forgiving in the turns, and is definately more tunable for the track conditions. Pretty soon I am going to really dig into this gto and see what changes can be made to the rear anti-squat and how far the camber can be adjusted. the front can go almost 4 degrees negative each side
I would probably not need that much, but the adjustment IS there. I'm lucky I have a buddy with a hunter digital 4 wheel alignment machine. So I can make fine adjustments for a track day test them, and set it back to stock If I want to drive it on the street. 
