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Bavarian Garage
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Switched to my winter set-up about 4 weeks ago, 17 inch square vs 18 inch staggered summers. I've got about 800 miles on them now and have noticed that my gas mileage has improved by approx 1.7 mpg! I'm loving it but wondering why. Driving me crazy trying to figure out if it's due to the narrower width, lighter wheels, softer compound, non-RFTs, different gas etc etc. This morning on my way to work, I'm cruising up the highway when it dawns on me, there's no technical reson why my mpg is higher, I'm DRIVING SLOWER WITH THE WINTER SET-UP! Keeping my speed at 60-65 mph vs 80 = 1.7 MPG. Took me a month to figure it out. :)
 

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Switched to my winter set-up about 4 weeks ago, 17 inch square vs 18 inch staggered summers. I've got about 800 miles on them now and have noticed that my gas mileage has improved by approx 1.7 mpg! I'm loving it but wondering why. Driving me crazy trying to figure out if it's due to the narrower width, lighter wheels, softer compound, non-RFTs, different gas etc etc. This morning on my way to work, I'm cruising up the highway when it dawns on me, there's no technical reson why my mpg is higher, I'm DRIVING SLOWER WITH THE WINTER SET-UP! Keeping my speed at 60-65 mph vs 80 = 1.7 MPG. Took me a month to figure it out. :)
Snow tires generally have miserable (high) rolling resistance vs. summer tires. Speed certainly makes a difference:
http://mpgforspeed.com/
 

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Livin' like Larry!
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I too have noticed about a 1 to 2 MPG increase since I switch to winter tires... But I haven't slowed down! :yikes:

I'm thinking it has to do with the width of the tires... My winter tires are 205s... 16 inch square... The only other thing is I'll admit that I did not check the tire pressures on my summer tires after having bought the car... perhaps they are low, but they all decreased equally, thus not upsetting the TPMS? It will be interesting when I re-install the summer tires in the Spring... I'll definitely verify the tire pressure at that time...
 

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Mysterious Fuel Economy...

Width of Tires...
Air Pressure...(it helps)
Colder air...(it helps)
etc.
Did you check out the graph (link) on fuel economy vs. speed?
Fuel consumption goes to "0" when you're stopped!
Snow tires have tread compounds that are highly "extended" with oils to keep them pliable in sub-freezing temperatures. This characteristic (high hysteresis) generates higher heat in the tread compound during operation, thus making them very inefficient in terms of low rolling resistance.
Any expectation that snow tires produce better fuel efficiency is a figment of your imagination.
 

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Breaking in the Pony
2019 Mustang GT / 2005 Toyota Tacoma
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The other reason gas mileage can drop during the winter in colder states is that the formulation of the gas is changed.
 

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I Know Nothing
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Judging by your username I'm surprised you didn't figure out the mathematical equation sooner.

"Yeah, driving slower. Definitely driving slower."
 

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HerrDoktorProfessor
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It could also be that all of your instruments (odometer, speedometer) is calibrated for 18 inch wheels. If you put a smaller wheel it will turn more revolutions whilst traveling the same distance. Thus you improved milage might be an illusion.
 

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It could also be that all of your instruments (odometer, speedometer) is calibrated for 18 inch wheels. If you put a smaller wheel it will turn more revolutions whilst traveling the same distance. Thus you improved milage might be an illusion.
It should be calibrated for the overall wheel/tire combination, the wheel size doesn't really matter as long as you are within a %ish of the original overall wheel/tire diameter. Assume that his setup is, the 17 inch wheel/tires combo probably has a smaller contact patch hence less friction, that simple. Thats why Econ cars have skinny tires. Of course slowing down helps too :drive:
 

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My last 3 cars have all been AWD and I have used winter tires on all 3 of them (Audi A4, Subaru Legacy GT, Infiniti G35 and now the BMW).

I have ALWAYS noticed improved fuel economy when driving on winter tires on all 3 vehicles with different types of winter tires. 3 cars, 3 years each, that's 9 years that I have consistently noticed improved fuel economy driving on the same exact roads. I can assure you it's not my imagination. It has always been about 1-2 mpg increase. I notice it most in a long (40 mile_ stretch of back road that I typically travel around 50 to 60mph.

I tend to think it's all the reasons mentioned above. Lighter winter wheels, driving slower, slightly different tire dimensions etc.


Ohhhh, one more thing. Vermont uses the same gas year round so no change in gas composition as far as I know. One less variable.
 
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