I took the 21" Uberturbine /Pirellis off my MYP at 73 miles and installed 4 255/40 x 20 Vredestein Quatrac Pro's on Velgen VF5 wheels. I don't have a lot of experiance with the Pirellis but have about 900 mi. on the square Vredestein setup. They're quiet, seem to have the same or better steering response, and the ride is smoother. As far as acceleration, they seem quicker from a standing start. This you would expect given a savings of at least 50# in rotating mass (12-13# per wheel). I'm sure the lateral acceleration was higher with the Pirellis, but the grip in a corner with the Vredesteins is high enough to scare this old 1960s muscle car guy. This is all based on my seat of the pants feel, and I have no data to back this up. So far I'm happy with this setup.