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View Full Version : AWD and staggered wheel setup



PJ Prendergast
01-30-2012, 09:49 PM
i figured i'd copy and paste my question to these forums, because you guys seem to be helpful

hey so some of you guys know i'm trying to run 18x10 and 18x12 wheels under my vr4, and since i've been suspended i had to do my research elsewhere. i found that as long as the difference in the rolling diameters of the tires i choose to run has to be within/under a 5% difference. is this correct?

my friend helped me calculate some tire sizes and differences, and these are the 2 we came up with (i'm not asking for opinions on tire stretch either, i just want to see if our math is correct and the effects on the VCU):

i could run a 225/40 up front and a 255/35 out back resulting with a 1.53mm rolling diameter difference.

or my cheaper way out (since i can't have a car as a freshman, i'm temporarily jobless and broke) is just change the rear tires to a 265/35 (my current fronts are a 235/something, i can't remember off the top of my head), but my friend calculated that difference to be 2.54mm.

my current setup (hasn't been run yet) is a 235/xx up front and a 255/xx (also forgetting those exact sizes at the moment) for the backs. i feel like this should be in that 5% range as well, but the other 2 options don't sound that huge of a difference. i would like to just get the rear tires (due to my current lack of income and impatience), but would a 2.54mm rolling diameter difference hurt the VCU? i mean i think that's in my 5% range but i'm not sure.

after asking 3si, the only response that answered my question was that i want/need less than 1% difference in revs per mile.... while on HERE i got a 5-10% difference

eventually i will have to get new tires since i'll be camber-wearing them anyways, but would either leaving my current set up or getting new tires impact my VCU that badly? friendly input is very much appreciated, thanks for reading

PJ Prendergast
01-30-2012, 09:58 PM
i got a more knowledgeable response on here, but i guess i'm just looking for some support on that response and other opinions, thanks!

teeceRS
01-31-2012, 10:23 AM
i can't explain why, but from my Subaru background, I've always been told by everyone that you can't run different diameters regardless of the run rate on and AWD platform; it'll kill your rear differential. Sorry I don't have any info about it. But I will try to find some if you'd like. Just for a third opinion?

PJ Prendergast
01-31-2012, 01:35 PM
yeah i've been told that i'll eat the VCU alive. when i bought the car it had 18's up front and 17's out back, nowhere near a close diameter and we drove it fine for a few weeks just to take it out haha (my dad and i fully restored the car and the tranny has been rebuilt)

kboers
04-11-2012, 05:14 PM
i can't explain why, but from my Subaru background, I've always been told by everyone that you can't run different diameters regardless of the run rate on and AWD platform; it'll kill your rear differential. Sorry I don't have any info about it. But I will try to find some if you'd like. Just for a third opinion?

I was told the same thing by my dad and he has been working on cars for 40 years now. Running different sized tires, even the smallest difference, will wear your differentials out.

The second paragraph in this article gives a pretty good explanation why
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=18

Minty_Fresh
04-14-2012, 07:24 AM
i run staggered on my audi. 18x8.5,9.5. no issues. but i have the same size tire front and rear. sure the stretch isn't even but that does not really bother me.

roof_rack
04-25-2012, 07:02 PM
It depends on the car, evo's / sti's are 2 solid diff's...you cannot run staggered widths / diameters on these cars, but offsets are okay within reason, the most important thing is to have the same contact patch. Audi's are okay though, plenty of people run staggered wheels on them without any issues.