For the uninitiated, the One Lap of America began as a legitimate way of paying homage to the Cannonball Baker Sea-To-Shining-Sea Memorial Trophy Dash that took place back in the 70s. Instead of making like Dom DeLuise and Burt Reynolds (or Sammy Davis Jr. and Dean Martin, for that matter), One Lap participants are lead around the country to a variety of racetracks, where the two-person team (sometimes three) then tries to set the best lap in their class. Modifications are allowed, but the competitors have to run on the same set of tires during the entire event. That not only includes the track time, but the rally stages in between that can sometimes last up to 24 hours.
Winding Road has the full breakdown of what's allowed, vehicle classes, rules, regs and the rest here and be sure to follow One Lap's progress here and here. Brock Yates insists.
[Source: Winding Road, One Lap]