Larger wheel diameter affect on MPG

2018t03

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Joined
Jun 13, 2011
Location
West Palm Beach
TDI
White/Black 2011 Jetta TDI DSG w/Nav
Does anyone have any realworld feedback on 17" or 18" rims and their affect on MPG vs. the stock 16" wheels? Also, does anyone know the weight of the stock 16" wheel? Thank you.
 

TDI_Convert

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Mar 31, 2004
Location
N. Central Indiana, USA
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Jetta Wagon 5 sp., 2003, Silver/Grey Int.
I can't help with 17's or larger, but I took a 2 mpg hit going from 15's to 16's. I got that hit back by going with lighter wheels, dropping down to wheels that weigh 12# each. The tires had no effect, I kept the same OD tire brand/compound and tread width on the pavement.

Check the weight of the wheels.
 

Vin63

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May 20, 2011
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SoCal
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Audi A3
The only affect would be if one wheel/tire combination is significantly heavier than the other (assuming the same size foot print), and the type of driving. The difference would come from the energy to move the higher unsprung weight of one of the wheel/tire combos. If you do mostly freeway driving, then the difference may be negligible.
 

JSWTDI09

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Jan 31, 2009
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Las Vegas, Nevada
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2009 JSW TDI (gone but not forgotten)
Usually when you go to a larger diameter wheel, you also change to a wider and lower profile tire. This keeps the outer circumference about the same which keeps the speedometer relatively accurate. There are several possible issues with this:

1) Wider low profile tires generally put a wider patch of rubber on the road. This increased size of the contact area does generate more rolling friction which can adversely effect mileage.
2) Lower profile tires have less "give" when you hit a rock or pothole because there is less tire there. This can lead to more easily damaged wheels.
3) Lower profile tires are often more expensive to purchase. Check on a website like tirerack.com and compare prices. For the same kind of tire, the lower the aspect ratio - the higher the price.

There can be exceptions to these rules, but they are things that you should be made aware of. If you are not going to be racing or autocrossing, the only advantage to bigger wheels is looks alone. If looks are more important to you than all of the above - then go for it.

Have Fun!

Don
 

geektoad

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Mar 11, 2010
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NH
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2010 Sportwagen
The effect of the wider contact patch is negligible. The majority of the hit people take is from the larger wheels generally being heavier. The extra rotating mass effects mileage an order of magnitude more than a "larger" contact patch. Keep the weight of the wheel/tire combo about the same as the smaller set and you won't see much difference.

(Larger in quotes because a wider, lower-profile tire does indeed have a wider contact patch, but it's also shorter front to back due to the stiffer sidewall)
 

TDI_Convert

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Mar 31, 2004
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N. Central Indiana, USA
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Jetta Wagon 5 sp., 2003, Silver/Grey Int.
I have to agree with the heavier rotating mass = less mpg. I added the Audi TT Brakes front and back, and saw a slight reduction in mileage. I had already put on 16" wheels on the car. By switching to lighter 16" rims, I negated the mileage hit from both the heavier 16" rims and the larger brakes. The first set of 16" rims didn't have enough clearance for the calipers, and they'd just barely tick against the caliper under spirited driving on the street. Problem solved with the new rims. I don't even know if they make the "new" rims anymore, they are 5 spoke SSR rims. The stock 15" wheels were 19.85# each, the first set of 16" rims were 19.90# each.

New/old front brake rotors


I looked, and I don't have a good picture of the light 16" rims......

I looked, and they still have the wheels listed on their web site
http://www.ssr-wheels.com/wheels/typec_171819.asp
 
Last edited:

2018t03

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Jun 13, 2011
Location
West Palm Beach
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White/Black 2011 Jetta TDI DSG w/Nav
Thanks for the feedback guys. I went with 17"s that weighed 21.9 lbs and from what I've read the stock Mambos weigh about 22 lbs so I should be good.
 
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