My Cub has a Maule SFSA solid rubber (non-pneumatic) tailwheel. I took the tailwheel apart to clean and lubricate it and I'm trying to figure out how, or if, I should lubricate the wheel bearings. The bearings appear to be pressed into the solid rubber wheel and don't seem to be removeable for service. The bearings spin fine and seem in good shape but I can't see any grease in them. Are they supposed to be greased? Oiled? Left alone until they just wear out then replace the entire solid tire with the bearings already installed?