Increasing Gas Mileage With Taller Tires? Options

[joyworks]

One of the few things that I dislike about my '99 Celica Convertible is that the gas mileage isn't as good as it could be. The 1997-2001 Camry, which had the same engine, got 3 mpg better on the highway with a 5-speed than my Celica does with a 5-speed, and the Camry weighed about 300 lbs more! I can only attribute this to the high revs of my Celica's 5th gear. So, my question is, can I achieve better fuel economy with a larger diameter wheel/tire combination? I know it would throw my speedometer off a bit, but to save fuel, it would be worth it to me. On that same note, what would would the tallest tire that I could put on a 16" rim and not suffer from any fender rubbing? What about a 17" rim? Thanks for your help!

[samir0189]

I'm not a physics major, but I'm thinking that the added weight of the tire will probably negate any gains that you may get from it. Especially if you intend to increase the wheel size, i think its important that you follow the "plus" sizing for both rim and tire where if you increase the wheel size you must decrease the tire profile, otherwise you'll increase the ride height of the vehicle, and the higher you are the more wind resistance you will encounter.