Hello I have a 94 Caravan and 94 Grand Voyager. Neither of these vehicles have a hitch standard but I had them installed at uHaul. The hitch rides so low that it hits and scrapes the ground sometimes on inclines and such. My question is what are the biggest tires that I can safely install to get a little more clearance from the ground without the tires rubbing? The vehicle standard is 205 70 15 & 15 x 6 aluminum rims.