hey im going to replace my rear tires soon because mine are bald and i was wondering what size to go for it has a 21x10x8 on it now but its hard to find new tires in that size so i was wondering if i go up or down in size what can i expect to happen different performance wise?? i ride on trails a lot and the skid plate sometimes gets hung up as it is so i really don't want to go down in size. any help you guys can give me will be greatly appreciated 
