Hi when adding the Gee fenders to a cub scout car our rules state as follows The distance from the bottom of the whee to the bottom of the car must be no less than 3/8 in in order to clear track runners the 3/8 in clearance also applies to any weights and or attachments on the bottom of the car does this mean the fenders cant be ran or do i need to do something else any info would be great boys derby is this weekend