Here are the Trials class rules:
2wd Class:
Basically any type of 2wd Monster Truck. May be front or rear wheel drive.
No limit on motors, batteries or suspension setup.
No limit on tire size or tread. Must physically fit on the course.
4wd Class:
Basically any type of 4wd Monster Truck. Only allowed ONE "serious crawling" mod.
("serious crawling" mods include, but are not limited to the following:
4 wheel steer, locked diffs, gear reductions or "dig" setups.)
More than ONE "serious crawling" mod and you need to move to 2.2 4wd or Extreme.
No limit on motors, batteries or suspension setup.
No limit on tire size or tread. Must physically fit on the course.
2.2 4wd Class:
This is for the 2.2 crawlers. Must be 4wd. Allowed to have 2 or more "serious crawling" mods.
("serious crawling" mods include, but are not limited to the following:
4 wheel steer, locked diffs, gear reductions or "dig" setups.)
No limit on motors, batteries or suspension setup.
Must use 2.2" sized rims/tires. Tread is allowed to be cut and modified, but not added to.
No limit on wheelbase or track width, but must physically fit on the course.
Extreme Class:
This class is for the "super class" type crawlers. Must be 4wd.
Allowed to have 2 or more "serious crawling" mods.
("serious crawling" mods include, but are not limited to the following:
4 wheel steer, locked diffs, gear reductions or "dig" setups.)
No limit on motors, batteries or suspension setup.
No limit on tire size or tread. Must physically fit on the course.