Just curious. Tire Rack as the pp version ranked first in the Max Performance Summer category, vs 8th (out of 23 total tires) for the non-pp tire. I called tire rack, but they didn't really give me a satisfying answer. The treadwear is the same, 140 for both tires. The tire rack description claims '90% higher silica content tread compound' for the pp's. I suppose that's the difference, I wonder if for a street tire it really matters?

 

At least from comparisons of the tires visually, the tread separation appears to have a much bigger spacing on the RE050A than the RE0505A PP (which translates into slightly larger tread blocks on the PP). It seems to fit with some of the descriptions I've seen of the RE050A being more of a performance coupe/sedan tire for good wet performance and the PP being more of the performance driving tire.

 

fwiw, i often troll bimmerforums' (esp track section) when researching tires. many more bmw guys race and track their cars and generally have good feedback on various tires for various uses.

SleepR1 had some good feedback on those tires RE050A. He is SleepRM3 over there.