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!

[blu94gt]

Thank you all for your comments so far. But, let's take the weight of the wheels out of the equation for now, as I will probably buy 16" rims that weigh about the same as the 15" stock rims anyway. If I were to consider the following two sizes from a low rolling resistance tire:

A) 225/50R-16 22 lbs. 831 revs/mile
B) 205/60R-16 20 lbs. 811 revs/mile

Do you believe that tire B would yield significant fuel economy improvement (1 mpg or more) over tire A? If not, then I guess I would go with tire A, as it would most likely handle better.

No, it will not yield significant fuel economy improvements over tire A. Even if it does yield you 1 more mpg, 1 more mpg on top of 32-33 isn't that big of deal. If we were driving Hummers and could find a way to get 1 more mpg, that would be great.