# Do bigger alloys affect MPG?



## Gulliver1 (23 Jan 2010)

Hi all,

I have a VW TDI Golf and I bought it for the purpose of maximising my MPG (fuel economy).

At present it has 16'' hubcaps on it and I am thinking about putting some alloys on. 
I am looking online and have found a set of 19's that have just come off a Golf GTI and am wondering will putting these bigger wheels on effect my mpg?

Thanks!


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## onq (23 Jan 2010)

*Re: Do bigger alloys effect MPG?*

Comfort, performance and mpg are likely to be affected.
The comfort negatively: especially with lo-profile tyres.
Performance negatively.
The mpg positively

ONQ.


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## Gulliver1 (23 Jan 2010)

*Re: Do bigger alloys effect MPG?*

Thanks dude


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## kieran160 (23 Jan 2010)

*Re: Do bigger alloys effect MPG?*

my advice would be not to put 19s on your golf, comfort would be greatly effected especially on minor roads. i have 18s on a 320d and i would not have them again. 19" tyres would be expensive. i would go with 17" on your golf! my mpg is down 3mpg compared to friends 320d with 17" alloys.


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## SparkRite (23 Jan 2010)

When moving from standards can be a lot more complicated than firstly appears so, just for starters read the following.........

http://en.wikipedia.org/wiki/Wheel_sizing


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## Frank (24 Jan 2010)

If the rolling diameter of the wheel remains the same then just the comfort should go down.

Just be wary of potholse. Bigger wheels will buckle much easier.


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## onq (24 Jan 2010)

Frank,

I take your point but the suggested increase in diameter was 3"...



ONQ.


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## Pique318 (25 Jan 2010)

When increasing the wheel size, the tyre profile decreases to keep the circumference as close as possible (but almost never the same) to the original. This means less rubber to absorb impacts from our rapidly disimproving roads. This also means your speedo will be a little less accurate.
Bigger wheels weigh more and require more effort to move, thus impacting acceleration and by extention, mpg.
19" wheels on a Golf will look good though, but I couldn't live with them.


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## RonanC (25 Jan 2010)

Pique318 said:


> Bigger wheels weigh more and require more effort to move, thus impacting acceleration and by extention, mpg.


 
Not always true, you can get lightweight alloy wheels which are a fraction of the weight of other alloys and alloys are lighter than steel wheels too.


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## sse (25 Jan 2010)

Few practical considerations before you consider MPG:
- if the new wheels/tyres are wider than the original then you may have clearance issues on full lock, plus the original GTI may have had a reduced suspension travel
- you will have to notify your insurance company of the modification
- larger alloys _generally_ overlap the tyre to keep the rolling radius as similar as possible, this means you have to be forensically careful with kerbs
- your speedo will probably underread compared to before (as I think in most cases this is taken off the final drive)

As for MPG, this is a difficult question to answer for certain. All things being equal a bigger wheel should move you further for one rotation of the engine, at the expense of acceleration. Not sure you'd experience much difference in real life as you may well overcompensate with the speedo under-reading.

Personally I think a 3" jump is a bit much on a standard Golf and is getting into Max Power territory, but it's all down to personal preference. Some cars look awful on their "standard" wheels - BMWs spring to mind - and an upgrade of an inch or so (remember the width goes up too) is well worth it. In any case I think you need tank tracks for the current state of many of our roads!

SSE


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## Gulliver1 (26 Jan 2010)

Hi all,

Thanks for the replies.

I did go to view a second hand set of 19''s but the vendor was incredibly shady. I brought my mechanic friend with me to view them. It turns out one had been welded, and another buckled! Additionally, they turned out to be replica's having been told by the vendor that they were genuine wheels and in ''showroom condition''. 

The search continues.... (!)


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