6 hour endurance without tire changes?

Can't go by just that. Depends more on the carcass design and temperature that the rubber is designed to operate at. I'd think an endurance slick would be you best bet. (But I ain't a real tire guru, and don't play one on TV neither.)

 

There are actually a few legal mods you can make to the bike to make tire changes faster. It isn't as extensive as Superbike, but it definitely helps. Read the rule book and if you guys come up with something have Mongo look at it to make sure.