So long as it is a street legal "slick" tire, it would count. I thought that they only allowed production vehicles on there anyway??
The Renault R24 went around the track in about 59.5 seconds or so, they did not keep that time as you could not purchase the vehicle.
Schumacher could still compete with the young guns in F1. His development skills, feedback for engineers, and overall team attitude were second to none in my book. When the car was up to par (and even when it wasn't) he could always wrangle the extra couple of tenths out of it almost at will.