You know who else slides better than your average drifter?
http://www.motoiq.com/magazine_artic...t-machine.aspx
The second photo on the page shows tires that appear to be properly sized. I suspect they have tried quite a few setups, at that level of sponsorship I wouldn't be surprised if they receive literally pallets of tires in the size(s) they request.
I'm not a drifter myself, and I generally disagree with the 'hella flush' style. That said, anyone who dislikes drifting should still go check out a Formula D event if you're able to. The paired elimination rounds after the drivers have qualified are a pretty entertaining display of car control and big horsepower. The cars aren't as cool a ALMS, but the track is set up in a way that makes it a really good spectator event (even compared to roadracing or NASCAR).