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!

[playr158]

I really don't think that the rpm difference is one you are going to be able to see on your gauge cluster. It will probably be even more insignificant since we are talking about 0.5" of height increase. As far as the drag coefficient goes, isn't it something along the lines of .01 per inch of height increase, so, .005 for half of an inch? Also insignificant. If you do end up doing this, I wouldn't expect even a noticeable difference in your fuel mileage, better or worse.

And d-man makes a valid point, this is unsprung weight, your engine will have to work harder to move those wheels.

wheels are not considered unsprung weight....you consider them rotational weight.
unsprung weight would only be the spring around your shock at a stand still

This post has been edited by playr158: Oct 23, 2008 - 7:08 PM