15inch vs 17 inch Mini lites
 

I just switched the factory 15 inch wheels that came on my 2011 Mini with 17 inch Mini lites. Instead of putting 205/45/17 on the Mini lites, I put 205/50/17 just to get a better ride. I am happy with this decision since even with the bigger tires the car rides better, BUT

I weighed both wheels and tires and what a difference in weight

15 inch wheel and tires = 29.5 lbs
17 inch Mini Lites with tires = 49 lbs.

That 80lbs more weight I am now carrying around. I have noticed a 15% decrease in MPG and less initial acceleration with the larger wheels.

That will happen with unsprung weight. I added light weight 17 Enkei RPF1's that are 14.6lbs vs the stock ones you have which weigh 25lbs or so. My mileage went up by about 2mpg.

The change in diameter may account for differences in Measured MPG or at least part of the difference noted.

Not only are they heavier, but now you're spinning more weight on accel and decel. Yes phoxx47, with the 205/50, he'll actually be driving more miles than indicated on the odo, so actual MPG will be better than calculated.

MINI OEM 15" wheels are 5.5' wide and factory tires are small and light.

17x7" wheels are much heavier, and 205/50-17 tires are 25.1" tire diameter which are oversized vs stock 17" tires. Your wheels are likely about 26 lbs each unless you are runflats which are heavy as well.

Less mpg is due to added rolling resistance with wider wheel and tire vs 15" stock.

For daily driving I use stock holey rims and 195/60-15 All Season tire.
33 lbs each corner.

For performance driving I switch to 17x7" (13.5 lbs each) and Extreme Summer tires. 37 lbs each corner.

Yes this is very true I quote this message because I had the same problem which you mention above. Then I change it according to the diameter which should be fix on it.

Did you have any rubbing issues with the 205/50/17s? I was doing the math and I think this size will just about fix the speedo error. What were your findings?

That size does not fix the speedo error. 205/45/17 is the stock size. A 205/50/17 tire will be 3.3% too slow. i.e When the speedo reads 60mph, you are actually going 62mph.

My speedo is 4mph fast at an indicated 65mph (actual speed 61 mph). So, yea this tire size would help fix my speedo error. I was looking for someone who has actually used this set-up.

Anyone have any rubbing issues?

What was the before and after with the speedo error?

Thanks

205/50/17
 

I have no rubbing issues with the 205/50/17 at all. But due to the decrease in performance and MPG, I sold the Mini lites and tires and now have 16 inch Rota's on my car. Currently I have 205/50/16s on the car. It does not look as good as the bigger tires, it actually rides rougher, but it is a a better fit for my needs. Since I bought the tires and wheels used, I plan to replace the tires next summer with 195/60/16 vs the normal 195/65/16s. The taller tires will fill in the fender wheel more and provide a better ride.

Sorry, i thought u meant the 205/50 vs stock tire size speedo difference.

Anyways, 205/50 17 should not rub if you have stock ride height.

SODA66: Yea, I'm concerned about the performance too. So I've got some Konig Feathers (16.4 lbs each) that I want to mount the Conti Extreme Contact DW (19 lbs claimed) for an increase of only 6 lbs at each corner. Hopefully the performance loss is minimal. Did you check the calibration of the speedo with the 17's?

Just an FYI... the speedo error is an addition that BMW does in the computer. Basically they add 3 mph to the actual speed. I have checked this with a gps. A tire size change will affect the error by a percentage of speed, so you can never really correct it, only improve it for the speed you consider to be most important.

There is an NCS Expert thread about correcting this in the computer.

speedo error
 

I have noticed that with my 195-55-16's that my speedometer reads fast but my odometer is spot on.

As I said BMW adds 3 mph to the speed. The odometer will be on as a result.

Hello everyone I am new to the forums would like to say hi to all, I have been reading as much rather I can absorb, I have just bought a 2009 cooper s in pepper white and as it is not my DDORSETT@DATCU.ORG for now I am trying to get some setup done, during my younger days when I lived in England going to school there is owned a few cooper s as you all now call the classic and use to race on the weekends, my most trophy one was a model cooper with full fiberglass body a 1.2L motor with 4 webber and I raced that car in the 5.0 class it was a very fun car to drive and cost me an arm and a leg, but long story short HI, on one of the posts I red that a member had just bought a JCW 2004 and was getting it setup he had mentioned something in the line of taking the 17's off and going with 15's. Why and what is the reason behind it since few other members were with him on his division.
Thx
Ben

Hi Ben,

15's offer lighter wheels, less expensive tires and a smoother ride.

The weight difference can be a huge change. The stock 17" MINI wheels can each weigh as much as 25 lbs and most are over 20 lbs. The 15" MINI wheel referred to as "Holies" weigh about 10 lbs. The difference in tire weight can be about 4 lbs. By going to 15" wheels and tires you can reduce the total rotating and unsprung weight by almost 80 lbs. Acceleration noticeably improves.

The stock tire size for the 15" wheel is 175-65. If you go to a 205-50x15 tire you will further improve your acceleration same as changing gearing.

The 17" wheels allow for larger brakes to be installed and a lot of people think they look better.