I started doing this before I made mud flaps. A trick I learned from ''WUDS'' on Revo-World. When the rubber boots are on the inside close to the bulkheads, there's less debris hitting them coming from the front tires. Especially running with a CD when the tranny unloads to the front wheels, they kick up dirt and rocks and throw them at the back of the truck at very high speeds. If you run mud flaps then it's not really necessary but I do it anyway because I'm just me