I just noticed that my gas mileage has dropped substantially (I'm talking about 4-5 mpg) the last couple of tanks, yet the only thing I've done recently is get new tires installed. I know they're inflated proberly because I checked it myself. Could the fact that they're 235/60 R15 vs 215/70/15 do it? Or could it be something else altogether. I've done a search and I couldn't find anything correlating tire size to fuel economy so I figured I'd throw it out here and see if anybody had any ideas. Thanks!