I am hoping some people can offer their opinion.

What are the benefits/negatives to running a 15 in wheel for track duty?

Here's my thoughts so far:
1. Lighter wheels/tires package.
2. Less expensive tires
3. Better tire selection (?)


Negatives:
1. Faster tire wear
2. Could it gear the car too low with the new gearing change in the 05 cooper S?



Thought? Need to make a decision soon! Thanks!!!

 

I think 15's are the way to go for track duty.
They have all the advantages you listed plus:

1. I think the lower gearing is an advantage, not disadvantage, as far as accelerating out of corners. There probably is a disadvantage in overall top speed - but this is much less important than improved acceleration on most tracks.

2. The 15s may fit in your rear hatch area better than other sizes which make them easier to bring to the track.

There probably will be a greater error in your speedometer, but I don't know that that matters much.

And I've never heard of 15" tires wearing faster than other sizes.

Good luck.

 

15's are definitely the way to go. Cost savings alone, in both wheel and tire costs are significant. If you're a casual driver, attending events infreqently it may not be worth the added cost of a seperate set of wheels.

If you're frequently attending events, however, the savings in tire cost will more than make up for it. IMO, there are no disadvantages at all. A smaller outside diameter tire may yield slightly less mileage because there is a little less rubber, but I wouldn't consider this a reason to stay away. The gearing reduction will be a welcome change since the Mini is geared too high to start with. Even if you were to reach a point where you're hitting redline at the straights, the car should still be faster and more enjoyable overall.

 

You've got it nailed. I don't see any reason to go for larger tires/wheels on the track except for big brake kits. Even then I believe the standard Wildwood kit fits 15" Kosei K1s which to me are the defacto track wheel with reasonable weight and cost plus easy to clean design.


Tom Der
2005 MCS Works
1991 M3
1990 535i

 

15's are proven performers! MY personal track stuff is 15 inch.

Alex

 

I have three sets of 15" wheels used for various autocross and track events.
1) autocross- Kosei K1 TS 15x7" with Kumho V710 205/50-17 High performance but wears fast, used only at the track for autocross runs.
2) Track Lapping sessions- Stock MINI 15x5.5" holeys with Michelin Pilot Sport Cups in 205/50-15 Good track tire but wears on the outer right front edges when pressed hard. Expensive, can be driven to the track, not for rain. Next time I'll be mounting Toyo Ra-1 in same size.
3) Autocross or track fun runs - Stock holey rims with Kumho Victoracer V700 in 205/50-15. A worn set from autocross I use for fun. Not as good performance but wears 2 or 3 times longer than V710.
4) You can also have a set of wheels with street tires that run well in the wet like Goodyear eagle F1 GS-D3 or Bridgestone Potenza S-03s

Other good tires for 15"
Avon Tech R in 205/50-15 and if your rim is 7" or 7.5" wide then 225/45-15 which keeps the smaller 22.9-23" tire diameter which really helps with gearing in any year MINI (MC or MCS).
Toyo Ra-1 is good for track but also can be used for autocross, but not as sticky as some others, does wear better and at full tread can be used in the rain. Best to shave down to 5/32nd" for best track performance.
Hoosiers and Kumho ecsta V700 are also available from tirerack.com

Wear on the 15" tires is OK, doesn't wear faster than other sizes. Just don't flatspot or spin your tires too much if you want them to last.

The small diameter is good and will work fine with any year MINI.
If I could go with 14" wheels that are wide I would but they won't clear the brake caliper. Big brake kits that useful on the track limit the wheels to larger sizes. Smaller BBK options are rather limited.

If you are considering SSR comps there are some non MINI fitments.
For the Miata there is a 15x7.5" rim (fits the MINI) but you can find it at tirerack by entering the wheel search as a Miata (just put on your Miata hat).