Vijay

Has anyone considred going with a staggered set-up to match the 60/40 torque split. 245/35/19 front on a 19x8.5" wheel and 275/30/19 rear on a 19x9.5" wheel would match up nicely. The tire sizes would fit perfectly on the wheels, and these wheel sizes are available in lightweight forged wheels that will fit the RS4.

Of course, the potential downside is increased understeer, but to what degree will this actually occur?

Any thoughts, input, ideas???

RI A6

This will reduce the grip of the tire during cornering. The rear contact patch will be a shorter length, increasing grip during cornering. The net results will be an amplification of understeer.

Running 275 tires up front will decrease the length of the loaded contact patch and increase grip, which will reduce understeer.

Here's the theory from Haney's book, The Racing and High-Performance Tire:

"Why Wider Tires are Better"

"For the same vertical load and internal pressure, a tire with a wider tread has a shorter, wider contact patch than a narrower tire. The area of both contact patches is the same if the internal pressure and load are the same. In the section on lateral tread deformation we showed that deformation builds up along the length of the contact patch until the restoring force of the tread and carcass exceeds tread grip and sliding begins."

"A shorter contact patch at the same slip angle begins to slip at roughly the same distance from the leading edge as with a longer contact patch. But the shorter contact patch has more of its length stuck to the road than the longer, narrower contact patch; and therefore a larger portion of its overall area is gripping. A larger portion of the contact-patch area gripping means more total grip. So for the same load and same slip angle, a wider contact patch generates more grip than a narrow contact patch."

larryV

I'm not saying that from experience because I've never tried a staggered set up, but since the car is already very well balanced with just a tiny bit of understeer on slower corners with the equal front-to-back tire/wheel sizes, I'd say if anything, adding more grip to the heavier nose would be more favorable than adding to the rear.

Like you said, who knows for sure to what degree a staggered set up will increase understeer but for my tastes, anything more towards that direction would screw up the handling of the car for me, especially at the track. The only possible benefit I can think of would be a better launch from a standstill when at the drag strip but who does that to their RS4 enough to make it worth it?

Bob W.

DEFAULT torque split is 40:60...quattro adjusts that based on available grip, and only if there's wheelspin.