My son is in red plate with a gear rule. Runs on asphalt, Jr sportsman Champ Kart. We are fairly new to karting. His times are coming down nicely and learning to be consistent on his line. His right rear tire has what looks to be feathering just on the inside quarter of the tire. Is that a sign of something that should be changed? His cross is 48%, right is 55% and nose is 45.5 %. Thanks for any comments.