front tire cupping

[Ray]

...there are some differences between the III and IV. The IV had a softer sidewall on the front tire, a more V profile of the front tire, a different silica compound on the rear tire and a couple of other small changes....

As usual, I agree with everything above, and would add, for me, all those changes added up to BIG differences in performance and longevity.

Though I only squeezed ~7000 miles and about 2 weeks out of my last set of RS4s, I'll be the first to admit that for many reasons including lack of skill, my tires usually take a beating in the twisty parts of life.

My first set of RS4s ran ~8000 miles, with 10% left.
I ran RS3s for only ~5500 miles, and a few sets of Roadtec 01s an average of ~6000 miles.