Not 100% true.b_a_betterperson said:The only conceivable delta would be the difference in the weight of the wheels.
Assuming they'd go +1 from 2454517 to 2454018...SJAndrew said:You would have more rotating mass but also a slightly different rolling radius too. The latter would provide slightly different gearing and conceivably better mileage.
I don't know where you are getting that, but it is simply not true. Even remotely. Saying that the larger the wheel the less economy, yet larger the tire sidewall, the better the economy is contradicting. If the sidewall is taller, the overall diameter of the tire is larger. So what is the difference between a larger wheel and a shorter tire vs. a taller tire on a smaller wheel?GTOooo said:unfortunately the calculator that I knew about which would tell you EXACTLY how much the difference is, is no longer available. The scientific explanation you are looking for is something I can't thoroughly explain very well but it goes something like this. The larger the rim size the less mpg you will get. The larger the tire (the 2nd number in a tire size, ie: 245/45/18) the better mpg you get. Sorry I can't be more explicit but I forgot the more detailed response. That pretty much sums up what you are looking for though I believe. So in conclusion 17 inch rims will get a slightly better mpg.