17" vs 18" Wheels and Fuel Mileage

GreekboyD · 11-08-2012, 07:42 PM

In the summer on my 18" wheels I'd be getting 7.5L/100 km or 31.4 mpg. Now with my 17" winter wheels I'm getting 5.4L/100 km or 43.5 mpg. This is highway mileage that I'm talking about.

It must be the tire size?

EYE4SPEED · 11-08-2012, 08:17 PM

Could be wheel weight or tire compound too.

GreekboyD · 11-09-2012, 06:28 AM

Quote:

Originally Posted by EYE4SPEED

Could be wheel weight or tire compound too.

These winters are heavier for sure, both wheels and rubber.

F32Fleet · 11-09-2012, 06:45 AM

Probably tire size causing the error but that's a significant difference.

Puerto Rican 335d · 11-09-2012, 07:11 AM

I believe its the tire size

DieselDiner · 11-09-2012, 07:27 AM

Tell us the tire sizes and let's use our collective brain power to figure this out! (uh oh)

GreekboyD · 11-09-2012, 12:26 PM

Quote:

Originally Posted by DieselDiner

Tell us the tire sizes and let's use our collective brain power to figure this out! (uh oh)

Summer:

235X40X18 - front

265X35X18 - rear

Winter:

225X45X17 all around

F32Fleet · 11-09-2012, 12:58 PM

Not enough to explain the discrepancy. I suspect sampling error.

PSEE · 11-09-2012, 01:32 PM

I have the same setup...

Maybe the colder air results in a mileage decrease? I thought the colder air was
'denser' and provided a better mixture (at least for gassers...) - what about
for oil burners?

DieselDiner · 11-09-2012, 02:05 PM

Most places also have a 'winter blend' that (from memory) supposedly reduces fuel economy. Don't know if that might contribute too?

GreekboyD · 11-09-2012, 02:24 PM

Quote:

Originally Posted by DieselDiner

Most places also have a 'winter blend' that (from memory) supposedly reduces fuel economy. Don't know if that might contribute too?

My fuel economy has improved in the colder weather and after the winter tires went on. Weird.

Pierre Louis · 11-09-2012, 02:40 PM

The difference could be a combination of lower rolling resistance, lower air resistance, higher air pressure, different diameter, and change in driving style. Dunno.

PL

DC-IT · 11-09-2012, 03:35 PM

Quote:

Originally Posted by GreekboyD

In the summer on my 18" wheels I'd be getting 7.5L/100 km or 31.4 mpg. Now with my 17" winter wheels I'm getting 5.4L/100 km or 43.5 mpg. This is highway mileage that I'm talking about.

It must be the tire size?

My D uses 17" for both normal and Winter tires and I do not have any difference in FE which averages out at 7.6 L/100 KM with a best tank average of 6.7 L/100 KM.

What is your range per tank (KM travelled per tank)?

What speed are you cruising to get 5.4 L/100KM?

When I drive on the 400 series in Toronto it is impossible to drive below 120 KM/Hr and in most instances I am driving at 140 KM/Hr which is why my average fuel consumption is around 7.6 L/100KM.

TDIwyse · 11-09-2012, 06:22 PM

http://www.caranddriver.com/features...d-tires-tested

Some interesting stuff in there that relates to your question.

Deed · 11-09-2012, 09:03 PM

Yup. In addition to the car and driver article there was a truck comparison a few years back. The results showed that by going from stock to larger wheels the truck lost 2 secs 0-60!

From personal experience, my LR3 lost a little over 3 mpg just going to a little larger tire!

scott135i · 11-10-2012, 05:54 PM

Are you going by the digital gauge or actual odometer reading based on fill up to depletion? Digital can be very off.

DnA Diesel · 11-10-2012, 06:43 PM

225 is likely the biggest effect, but there is something going on more than just that...probably driving habits and average speeds, as well.

In the summer, I average ~7.2-7.5 mixed with 235/255 18's. So far, I see 6.9-7.3 with the winters and similar driving habits. 235/255 > 225 is a noticeably narrower width and likely influences consumption.

The only way I ever get into the 5.3-5.6 range is by driving at or below 100km/h...not a very easy thing to do in this car.

Cheers
D.

11-08-2012, 07:42 PM	#1
GreekboyD Brigadier General 411 Rep 3,049 Posts Drives: 2009 BMW 335d Join Date: Jan 2012 Location: Toronto, ON, Canada iTrader: (0) Garage List 2009 BMW 335d [8.00]	17" vs 18" Wheels and Fuel Mileage In the summer on my 18" wheels I'd be getting 7.5L/100 km or 31.4 mpg. Now with my 17" winter wheels I'm getting 5.4L/100 km or 43.5 mpg. This is highway mileage that I'm talking about. It must be the tire size?
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11-08-2012, 08:17 PM	#2
EYE4SPEED Ex-Diesel Driver 63 Rep 2,000 Posts Drives: Audi SQ5 Join Date: Apr 2010 Location: West Coast... of Michigan iTrader: (22)	Could be wheel weight or tire compound too. __________________ FS: HRE Center Caps http://www.e90post.com/forums/showth...post13972317l]
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11-09-2012, 06:45 AM	#4
F32Fleet Lieutenant General 3570 Rep 10,350 Posts Drives: 2015 435i Join Date: May 2005 Location: Southeastern US iTrader: (0)	Probably tire size causing the error but that's a significant difference.
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11-09-2012, 07:11 AM	#5
Puerto Rican 335d Brigadier General 229 Rep 3,489 Posts Drives: Montego Blue 335d Join Date: Jun 2011 Location: Puerto Rico(Dominican Republic 03/2017) iTrader: (0)	I believe its the tire size __________________ RENNtech Flash(Lenny Wu)/WAGNER IC Enkei Rajin 18"/Execuhitch Hitch/Koni FSD Soft Ride Bike Rack/Brava Synthetic Motor Oil(Made in Puerto Rico)/Meth(in the works)/CBU done w Andrew EGR Race Pipe (whoa! what an animal it is now)
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11-09-2012, 07:27 AM	#6
DieselDiner Lieutenant Colonel 486 Rep 1,614 Posts Drives: 335d Join Date: Aug 2010 Location: Home iTrader: (2)	Tell us the tire sizes and let's use our collective brain power to figure this out! (uh oh) __________________
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11-09-2012, 12:58 PM	#8
F32Fleet Lieutenant General 3570 Rep 10,350 Posts Drives: 2015 435i Join Date: May 2005 Location: Southeastern US iTrader: (0)	Not enough to explain the discrepancy. I suspect sampling error.
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11-09-2012, 01:32 PM	#9
PSEE First Lieutenant 12 Rep 332 Posts Drives: 2009 335d Join Date: Dec 2010 Location: BMW, MA iTrader: (0)	I have the same setup... Maybe the colder air results in a mileage decrease? I thought the colder air was 'denser' and provided a better mixture (at least for gassers...) - what about for oil burners?
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11-09-2012, 02:05 PM	#10
DieselDiner Lieutenant Colonel 486 Rep 1,614 Posts Drives: 335d Join Date: Aug 2010 Location: Home iTrader: (2)	Most places also have a 'winter blend' that (from memory) supposedly reduces fuel economy. Don't know if that might contribute too? __________________
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11-09-2012, 02:40 PM	#12
Pierre Louis Captain 158 Rep 866 Posts Drives: 2016 535d Join Date: Apr 2012 Location: Savannah GA iTrader: (0)	The difference could be a combination of lower rolling resistance, lower air resistance, higher air pressure, different diameter, and change in driving style. Dunno. PL
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11-09-2012, 06:22 PM	#14
TDIwyse Colonel 614 Rep 2,410 Posts Drives: 2011 335d Join Date: Aug 2012 Location: MidWest iTrader: (0)	http://www.caranddriver.com/features...d-tires-tested Some interesting stuff in there that relates to your question.
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11-09-2012, 09:03 PM	#15
Deed New Member 1 Rep 17 Posts Drives: 335d Join Date: Sep 2012 Location: Ohio iTrader: (0)	Yup. In addition to the car and driver article there was a truck comparison a few years back. The results showed that by going from stock to larger wheels the truck lost 2 secs 0-60! From personal experience, my LR3 lost a little over 3 mpg just going to a little larger tire!
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11-10-2012, 05:54 PM	#16
scott135i Colonel 355 Rep 2,080 Posts Drives: 2020 X5 M50i Join Date: Feb 2009 Location: NYC Metro iTrader: (12)	Are you going by the digital gauge or actual odometer reading based on fill up to depletion? Digital can be very off.
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11-10-2012, 06:43 PM	#17
DnA Diesel Major 27 Rep 1,110 Posts Drives: 09 335d Sport SGrey/Blk/Blk Join Date: Dec 2009 Location: Ottawa, Canada iTrader: (0)	225 is likely the biggest effect, but there is something going on more than just that...probably driving habits and average speeds, as well. In the summer, I average ~7.2-7.5 mixed with 235/255 18's. So far, I see 6.9-7.3 with the winters and similar driving habits. 235/255 > 225 is a noticeably narrower width and likely influences consumption. The only way I ever get into the 5.3-5.6 range is by driving at or below 100km/h...not a very easy thing to do in this car. Cheers D. __________________ 2016 GLE 350d - White on Black
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