New to forum and just purchased a 2010 prius. Not really digging the stock wheels. I have been searching for the lightest 17 inch wheel and tire combo and have found one totaling 35 lbs, which is about 3 lbs heaver than stock. My question is, the overall width of the tire will be going from a 195 to a 215, which will equate to almost 3/4 of an inch more rubber on the road. Will the extra rubber on the road decrease mpg by much, or will it be to small to worry about.
I think it will be a small difference. If you are really worried, look to purchase some low rolling resistance wheels. The only problem here usually is finding one that will fit a 17" wheel.
For reference, the MPG hit for the OEM 17" vs. 15" wheels is ~1.25 MPG (per the UK spec sheet). To me, the 2.5% hit is a rounding error, but others here have varying views. Whether the tires you're considering will increase rolling resistance depends on which tires you have now, and what the rolling resistance of each is. The extra width and unsprung weight will likely increase rolling resistance, but not necessarily--if the new tires are very efficient compared to the current tires.
Check my math: 15": assume 12500 miles a year, @ 50MPG annual average = 250 Gal used 17": 12500 / 48.75MPG = 256 G Let's round up to 10G of extra gas to be less optimistic. If you're trying to be environmental then every bit counts. If you're trying to save money, then it's not even worth worrying about. You wouldn't be buying rims if you can't buy another $30 a year of gas.
All other factors being equal, wider tires will get worse mileage. Perhaps not a big hit, but they all add up over time. Tom
I have done the math. Go ahead with the wider tires, just be sure to empty your bladder before driving and you shouldn't notice a difference in MPG.
