I have a set of Pirelli PZero Nero M&S (approx. 5k miles) installed in the rear and are looking to replace the front tires with Kuhmo ECSTA ASX. Although they’re both ZR’s Ultra High Performance All-Season tires the Pirelli PZero Neros are classified as 91W UTQG: 400 AA and the Kuhmos are 94W UTQG: 420 AAA. Is this difference going to significantly affect the ride quality and traction handling? Thanks in advance for your help. I have a 1998 E36 M3 with a set of 17” staggered contour wheels.

I think you're OK with this setup for street driving.