YUL PHL

iTrader: (1)

hi all,

I just switched over my stock 18's to my winter 17's set up

I noticed a substantial increase in mpg.

so, i was wondering if any of you have ditched the stockies and gone with light weight 17s and if you've noticed a difference in your mpg?

Rotary-RX8

iTrader: (1)

i wouldnt doubt it. 17 = usually lighter which means less rotational force (if thats the correct term) which means better mpg.

YUL PHL

iTrader: (1)

was begining to consider trading it in and getting something more fuel efficient sicne i got a new job which is a bit further away.

will prob. get a tire/wheel combo next spring.

looking @ 5zigens or work emotions for light wheels

mrl84

if the OD of the tire change the milage would change, ie if your winter 17" wheels dont have an inch more of total sidewall than your summer tires the OD got smaller. if thats the case and the OD is smaller your car will report more miles than it did with the summer tires (for the same trip), but the actual fuel used is probably about the same so you get a reported higher MPG...

i know my 17" winter set up is about 4% smaller in OD than the Stock setup was and they definatly weight more but i got a higher mpg because of what i explained above.

Wingznut

iTrader: (1)

mrl84 nailed it... If the total circumference of your tires are a little smaller than your stock ones, your odometer will falsely read more miles.

The possible reduced weight or reduced rolling resistance of your new tires could contribute to more mpg, but most likely wouldn't be significant.

NotAPreppie

Moving mass from the edge towards the center reduces moment of inertia. Moving the metal hoop of the wheel inward should accomplish this though the difference should be smaller than the error bars on your experimental method.

Odds are, something else changed (most likely in the driving conditions) to account for this.

monchie

Smaller wheels means lighter weight and will affect the gas mileage by a fraction. We all should get smaller wheels to save on gas...lol

YUL PHL

iTrader: (1)

****. just thought about it and you're right. my winter set up is a bit smaller than my OEM 18's.

i was expecting my winter tires to be heavier and have more resistance, thats why i was surprised by better mpg

silly me