Quote:
Originally Posted by mpg_numbers_guy
Welcome to ecomodder. 
245/40R18 are giant tires/rims. You would likely see a larger benefit going to 15" or 16" rims and narrower tires. 245/40R18 could be replaced with, say, 215/65R15 tires. 1.2% taller gearing, but more importantly a far lighter and more eco setup.
Wider tires almost never help economy unless you are comparing a wider, low rolling resistance tire to a narrower, non-eco tire. The heavier weight of a taller tire may hurt economy in the long run unless you do only highway driving. |
I know most would think I'm silly for purchasing a higher performance car and giving a hoot about it's gas mileage. But sadly, I'm an odd person with odd tastes. With that said, thanks for your suggestions. However switching to a different rim size is not an option for me for two reasons. First, I would lose cornering grip which I do not want to do. Secondly, I have larger brakes than average, thus shrinking the barrel size of the rim will not work. I plan to stick with 18" wheels.
With that said I won't go smaller than the 245mm width I currently have. If I get the wider rims(9.5") I'll eventually move up to a 255mm or 265mm tread width. I'm really just trying to gauge how costly the wider tread will be to my MPGs.
I recently got some Michelin X-ice tires for my winter set. I thought they would tank my MPGs. However I was wrong. They maintained a similar, or at least non perceivable, difference in MPGs. The cold weather had far more impact than the tires. I'm wondering if my tread width will be a similar difference. Too small to notice. Or if lightening the wheels 4 lbs. each will have such a positive gain, that the increased rolling resistance of the tires will be over shadowed.
Thanks again for your suggestions.