veteq

does the RS4 need to have the same tire ratio front and rear?

I am just curious coz the R8 is using 295/30 rear and 235/35 front which is not the same ratio. R8 is 4wd so why it can use different ratio?

ghoonk

on the evo, you should never run a staggered layout or risk damaging the differentials.

You've made a good point. I wonder if Audi built it such that the slip is calculated and accounted for in the diffs...

bpp

Simply put from my simple mind: the R8 stagger is necessary to control the weight bias (rear) and differential (front-to-back) bias of a mid-engined, oversteering, AWD car for better rear bite, neutral balance and control.
RS4's got about 58% of its weight on the front and inherently understeers. Therefore you do NOT want more traction over the rear wheels but on the front, and opposite of what's needed on the R8 or any mid-engined car (generally speaking). Better to have the fatter tires over the front to get more traction which will help reduce the understeer but will look very silly. To overcome the understeer (and be aesthetically pleasing) in other ways one can add coilovers with much stiffer rear springs (or stiffer rear spings), a stiffer rear sway bar, and adjust rear tire pressures a few pounds higher than the front pressures.

Vijay

Going to a staggered set-up on the RS4 would tend to increase understeer.

However.......

If you were to run an aftermarket set-up like Stasis, much of the understeer would be reduced anyway. In that circumstance you could go for a 19x8.5 front wheel with a 245/35/19 tire and a 19x9.5 wheel in the rear with a 275/30/19 tire. You may want to use spacers up front to increase the track width of the front and help counteract understeer even more (and for aesthetic purposes)

This may be an ideal set-up. The slightly decreased rolling dimeter would also correct for the 2-4mph falsely high speedometer reading that the RS4 gives.

bpp

2-4 mph optimistic speedo reading seems synonymous with VAG products, my S4, my TDI, my P-sat 4mo.

BergeyRPI

<ul><li><a href="http://www.nyracer.com/overunder.htm">http://www.nyracer.com/overunder.htm</a</li></ul>

BergeyRPI

A decrease in rolling diameter would make the speedo even more optimistic.

bpp

You want more bite in the front, less bite in the back to rotate the ***-end...fronts come down (larger contact patch, more grip) and/or rears go up (smaller contact patch, less grip)...for a car with inherent understeer. Front plows because the front tires not working hard enough. Check it. Softening the front spring rate's another way, remove the front sway bar too. You want to "harden" the rear bias so it works less and follows the front, rotates better.
Remember you are 'plowing' when you understeer and want the tires to grip more to get away from it. Or redistribute the weight which isn't a simple task on a street car piggy like we drive.

Vijay

I think you are right.....I may have been thinking backwards !!

Vijay

Great link !!! Might have to add 10 mm spacers up front.