I recently put a new Harbor Freight 6.5 engine on my Baja Doodlebug and it is amazing!! Problem? I live on a dirt road and the rear wheel bogs down into the sand. I was wondering if it would be possible to put new and bigger tires on the bike instead of the regular 145/70-6 tires that are on there now? There's only about 2 inches of free area from where the tire touches the ground and where the chain is. Anyone else having this problem? Please help!