Questions and Answers

New Tires For A GMC Sierra 4X4 Q. Hello! I drive a 2001 GMC Sierra ¾ ton 4X4 long box with an 8.1 litre gas engine and an Allison 5 speed automatic transmission.The truck came with LT 245/75R/16 A/T tires and a 4:10 rear end. Could I get better milage by going to taller, wider tire and if so what size could I go to without changing the speedometer. What would the rear end ratio be in effect if the tires were changed? Thank You, Darryl

A. A taller tire may get you more top end rpm range but I doubt that any increase in fuel mileage would be noticed. Also, a wider tire may look better but will create more drag and nullify fuel savings. Any size change will change speedometer accuracy. You may want to look into a bolt on overdrive unit instead.