I've got a 97 explorer. I'm getting ready to buy some new tires for it (at Fords expence). Right now I've got the 235/75/R15 Firestones on the stock 7 inch wheels, but I would like to replace the tires with something a little wider. What size of tire would be a little wider than a 234/75/R15, but still have the same outside diameter? I don't want my speedometer to be way off. Any information would be great. Thanks.