ok on our track most run the 150 motek some stock & xray chassis i run the eits chassis. the track is about 100x36. we run the stock diffs with no problems. we use hand cleaner for the tires works great. our cars have to be 15oz. or more. my car is 15.5. i run ajustable shocks all around & ride height is 3mm at the most with about 4mm travel all together. as for the bearings i clean mine about 2 or 3 times a season running only 1 drop royal oil in them with no problems & run only 1 side of the bearing shield to help keep dirt out.