I can't tell you exactly what 32/33 in. tires will do to your vehicle mpg. How are you going to get those to fit? My 31x10.5x15 AT tires fit well without rubbing and I didn't have to cut anything to make them fit, but it's a big jump to go anything higher than 31's, in my opinion. It will decrease you mpg due to the fact that your engine has to work harder to help push those bigger heavier tires down the road. I'm not saying that you're going to lose 5 mpg, but it will do a little bit of damage to your pocketbook here and there. In reality though, if you're wanting to do it for looks, combined with a lift, bigger tires are better. If it is your daily driver though, it would be better to get a terrain tire with close to OEM size or no bigger than 31's. Hope this helps.
