Are 17" wheels more efficient (MPGwise) than 18s???

anerbe · 01-10-2011, 07:56 AM

too many factors in play to pin it only on wheel size

things that decrease rolling resistance
- thinner tires (less air drag and smaller footprint)
- smaller wheels (less rotational mass)
- less tire siping (summers are lower than winters)
- tire compounds (unknown between tires)
- cooler weather (stiffens rubber = less flexing)
- lower tread depths (summers are lower than winters)
- lighter tires (depends which tires are RFT)
- tire specs (XL tires are worse due to weight from reinforcements)

etc.....

I saw a 1 mpg drop between my 19" BBS with 245/275 summers and 18" stock with 245 square winters on my M3.

It did help that the 19" were about 4 lbs lighter a wheel vs. stock.

Quasimodem · 01-11-2011, 12:50 AM

Quote:

Originally Posted by John 070

Quote:

Originally Posted by Quasimodem

Are we talking about larger rims here or wider tires? I would say that wider tires will make for worse mpgs, but a change in rim size by itself shouldn't affect mileage.

It's uncanny how people speak in theory and not application. A 18" rim could possibly be 5 lbs. heavier each corner, for a total of 20 lbs. And the OP draws the conclusion that he gained 10 mpg as a result of going to 17's. I think maybe a reality check is needed, or a better understanding of calculus. On my Nissan, I have gone from 16, to 17, to 18, back to 16. No change in mpg whatsoever.

I thought the idea of larger rims was to reduce wheel weight. Isn't al lighter than rubber? Bigger rims means less rubber and lighter wheels, right?

Coolieman1220 · 01-11-2011, 08:21 AM

A lighter rim and tire vs a heavier one is best. less weight = less power to accelerate and break, therefore better gas mileage.

a 17" rim and weight as much or more than an 18" rim. If it is lighter, same size, same tires it will make a difference. unsprung weight is a huge factor.

typically smaller rims are lighter than bigger rims. although you need a bit more sidewall, that doesn't make a huge difference because rubber is lighter than metal.

THE END!

01-10-2011, 07:56 AM	#23
anerbe Lieutenant Colonel 124 Rep 1,567 Posts Drives: Red E90M 6MT Join Date: Dec 2006 Location: BH, MI iTrader: (2)	too many factors in play to pin it only on wheel size things that decrease rolling resistance - thinner tires (less air drag and smaller footprint) - smaller wheels (less rotational mass) - less tire siping (summers are lower than winters) - tire compounds (unknown between tires) - cooler weather (stiffens rubber = less flexing) - lower tread depths (summers are lower than winters) - lighter tires (depends which tires are RFT) - tire specs (XL tires are worse due to weight from reinforcements) etc..... I saw a 1 mpg drop between my 19" BBS with 245/275 summers and 18" stock with 245 square winters on my M3. It did help that the 19" were about 4 lbs lighter a wheel vs. stock.
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01-11-2011, 08:21 AM	#25
Coolieman1220 Banned 76 Rep 1,770 Posts Drives: 2010 335d Join Date: Jul 2010 Location: New York City iTrader: (0)	A lighter rim and tire vs a heavier one is best. less weight = less power to accelerate and break, therefore better gas mileage. a 17" rim and weight as much or more than an 18" rim. If it is lighter, same size, same tires it will make a difference. unsprung weight is a huge factor. typically smaller rims are lighter than bigger rims. although you need a bit more sidewall, that doesn't make a huge difference because rubber is lighter than metal. THE END!
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