Um, who is assuming that when the tread wears down, laptimes would be slower? I'm assuming nobody is really aware of the findings (mainly at the Indy 500) where the cars got faster with reduced tread. Edit: Didn't this even happen with the treaded tires in F1 in the late 90's? Where the intermediates would wear down to slicks? Tires are complex things, I think people should stop assuming all tires and situations have the same outcome. This is part of rFactor2. You're in an evolving race situation, with many factors. Some may counteract each other, some may not.