Going to take a wild guess that GTR aren't generally owned by the kinds of people that do winter setups... Ben will probably be the first one in this area.
After dumping a ton of money on his Z, and now a GTR I'm sure the last thing he wants to do is put Blizzaks on huge oem rims... Has to be something reasonable he can do, and is worth a shot IMO.
Someone at Vinny Ten, or Performance can probably help him out...
Edit in... If people are doing GTR wheels on 370z, why not the other way around?
GT-R wheels on 370z?