[Yellow Belly]

We have just changed our steel 15" wheels for a set of S-lites with runflats. Fuel consumption has plummeted by about 7 or so mpg. We will be refitting the steelies to see if the formerly good 56 mpg will return. Sometimes we got 62 mpg on steel rims, but now 47-48 is the norm.

Any one else noticed how detrimental the 17" wheels are to fuel consumption? Can you fit even thinner tyres than the standard ones to improve mpg?

[Paul]

The 17" (s-spoke) wheels and run flats are also very heavy, that wont help at all. Why anyone would chose to go to those from 15's (maybe the 16's which are a good compromise) is a bit of a mystery to me.

[Axtell]

Is it the weight of the wheel that is the problem? Or some other factor? I have looked around and a set of 17" wheels weighing less than 20 lbs. per can be had for $500 or so.

[Yellow Belly]

Quote: Originally Posted by Paul Mullett

The 17" (s-spoke) wheels and run flats are also very heavy, that wont help at all. Why anyone would chose to go to those from 15's (maybe the 16's which are a good compromise) is a bit of a mystery to me.

The steels provided with the ONE D are a bit basic. The S spokes are a lot more attractive, IMHO perhaps one of the most attractive wheels on the MINI, however that is personal choice. What was not expected was the huge difference in fuel economy on the ONE D. We just assumed that the drop might be more like 2-3 MPG, not 7+!

So do owners of petrol driven MINIs see such a large drop in fuel economy, or is it just the diesel? If its not a problem on the ONE, then I could swop wheels with its 15" 8 spokes perhaps?

[brett]

I really like the ride that my Mini Cooper gives with 17" wheels.
With the mix of 17" S SPokes and the softer suspension.
Looks great and rides well a tad more bouncy though

[northandy]

I wouldnt have thought the weight change even though the S spokes are notoriously heavy would have made that much difference, maybe the gearing is affected by the change in diameter ?... will be interesting to see your results with the steelies !...

[Paul]

Doh! I posted in black again. Must fix that little problem.

Anyway, it's not merely the weight "on the scales" you have to consider, consider also the fact that the power is used to turn those things around, and spinning four larger, heavier wheels will be much tougher than spinning four smaller, lighter wheels. Same with stopping, but that's not really an MPG issue of course. Then, as others have pointed out, you've got a larger contact area, and more 'actual' drag due to the area that's facing into the oncoming wind....

7 mpg does seem a lot, but it's not too surprising to me.

[swamos]

It just occurred to me that if your wheel alignment was out on your MINI then the drag would be much more noticeable with the larger grippier tyres. When was the last time you had your 4 wheels aligned??

[Pepper'D]

mines running at 48-49mpg on 17" s spokes falken tires

[R1]

Quote: Originally Posted by Paul Mullett

The 17" (s-spoke) wheels and run flats are also very heavy, that wont help at all. Why anyone would chose to go to those from 15's (maybe the 16's which are a good compromise) is a bit of a mystery to me.

Form-over-function my friend!!

Never known what MPG my Cooper does! Not that interested to be honest!

[Martin L]

On my new MCS which now rides on x-lites I'm getting about 3mpg more then my old MCS on s-spokes.
I thought it might be the new engine software, but after reading this thread I'm sure it'll be down to the wheels

<------pleased at the extra beans he's saving

[northandy]

Quote: Originally Posted by Martin L

On my new MCS which now rides on x-lites I'm getting about 3mpg more then my old MCS on s-spokes.
I thought it might be the new engine software, but after reading this thread I'm sure it'll be down to the wheels

<------pleased at the extra beans he's saving

not too mention how much you'll save when you need new tyres !!!....

[Huck BB62]

With a 7mpg decrease in mileage, did you notice a huge loss in performance? It would seem to me that losing that much mileage, you'd expect to see a big loss of power.

[Boomer]

Hmm, was thinking about getting new wheels and tires. I'll wait till after winter but this will make it easier to talk my wife into letting get them. Thinking about Kosei K1s and Yokohama ES100s, if any has experience with this combo info would be appreciated.

Boomer

[Charger_Pete]

Changing the wheels to 17's would account for 3 to 4% max reduction in fuel economy. Going by your figues, FE has dropped by a massive 12.5%!! The increased rolling resistance and mass would account for the small change but not 12.5%. Swamos has a valid point that the wheel alignment could be wrong.

I am not sure if the rolling radius of the tyre changes by going from 15's to 17's. Has your mph/1000rpm changed after fitting the 17's?

[brett]

no not really, It's got me buggered Taking it to the dealers next week so i'll get them to check the tuning. perhaps I May be able to talk them into giving me the Works Cooper Software

[JME]

I once had a car to which I fitted a known good high flow exhaust... and my fuel consuption got significantly worse. It turned out that because I liked the noise of the exhaust I was driving the car harder without really being aware of it. Perhaps this is the same thing. Maybe the car handles better so you are driving it harder without noticing it.

[Spookyfish]

Besides the weight, the wider tires have more: air resistance and rolling resistance.

[bryce03]

Im sorry but if ur going to be that tight buy urself a 50cc moped, if my new mini only does 10mpg i dnt care, its got big 17"s and id rather pay extra money for diesle so she looks cool!