I thought i read in there somewhere that they cant stick out past the widest part of the tire...
Found it under the FXT rules but im not sure if it applies to all the other classes. It would make sense if it did to avoid slashing other peoples tires if you rub up against them...
12.BODY: Body can be home made but must resemble a lawn tractor. No sharp edges. Rear fenders must not be
wider than the bulge or widest part of the rear tires.