I've done a decent amount of searching through the archives of both NAM and MINI2 and haven't found a clear cut consesus as to what wheel size has preference over others for track days. I have run 15" (with pilot sport cups) on my M3 , and don't have any problem doing that with the MINI as well. There is a chance I may upgrade to a BBK, but I would probably use the standard wildwood kit which seems like it fits at least some 15" wheels and more importantly will clear my stock 16" wheels with snow tires in the winter. Otherwise i'm really not too particular, cost of tires/wheels is not a huge issue.

I'll probably end up using Kumho MXs due to low cost and pretty good performance as my tire choice for these wheels as I plan to mount them the evening before the event and drive to the track and will probably forgo R compound at least initially. (Can you fit 4 wheels with tires mounted in the MINI hatch?).

Thanks in advance to any and all who want to weigh in on this issue.

Tom Der
North Hampton, NH
2005 MCS Works
1991 M3
1990 535i

 

The smaller the tire diameter, generally, the cheaper the tires.

195-60-15 has some moderate performance tires at cheap prices.

If you go to 17" diameter, there will be a small selection of tires
narrow enough to fit a MINI.

I'm happy on 16" rims.

And you can fit a lot in a MINI.

 

but someone makes a retaining bar that will hold 4 wheels and tires in the back of your car without bouncing around. Search and ye shall find! I don't remember where I saw it.

Matt

ps, some also are talking about a small trailer for tires etc for track days.

 

I think 15's are fine, especially if you're going to a wide 15" wheel, like a 7 or 8 inch width. I don't see any reason to run anything bigger than 16 if 15's don't do it for you. I think there are a fair amount of 225 width 15" 'R' compound tires this year, so I don't even really think 16's are necessary.

Myself, I'm big into autocross, more than track days, so I bought some 16's for my Cooper this year so I could run wider wheels (for autocross classification, I can choose between the 15x5.5 or 16x6.5).

I get 4 tires and my gear in the back of my car. I stack two of them horizontally in the center, then put one vertically on each side, and then use some tie-downs to strap them all together so they don't move around.

Then I can get the jack and all the other junk in right behind the hatch.

 

My understanding is that you want smaller wheels for auto-x and larger for track and road racing.
Auto-x is low speed and quick acceleration where as track days is high speed. If you run 15" on the track you might get killed on the straights.

15 for auto-x, 17" for track

 

I think it was RDR that made the tire bar. It latched into the seat catches. It is not on their web site any more.

John

 

Yes, RDR definately made one. I autocross with one of the RDR guys sometimes, and I've seen it in his car.

Onasled - I'm not following the logic of how bigger wheels help in straights? The larger diameter means you can go faster in a particular gear? But then you'd be accelarating slower

I'm far from a track expert, but I always figured you basically ran the smallest wheels that would fit over the brakes that you need. Since I run a 115HP stock Cooper, I don't ever get going fast enough to need anything other than stock brakes

 

You're gonna ket killed on the straights in a MINI no matter what the tire size you use. It's in the corners that you will shine:smile: You are gonna want to get all the power down you can as you accelerate through the apex. Remember you are driving a front wheel drive, and as long as you are pulling, the rear wheels will follow. I have tried 16's and 15 inch holeys on the track, the 15's are way better.

 

I have a set of "stock" 16s that came on the car, and a set of "Stock Size" 17's on a set of stock rims.

The Outside diamater of the tires is the same. If you go larger than stock, you have to watch for rubbing. There is a thread about that around here probably under "tires and wheels".

AS for the tire bar. Ron now trailers his car and does not need the tire bar anymore. If you contact RDR they might have one left, or used for sale.

John

 

My understanding is that you want larger wheel in track just to fit larger brakes, which will help with lots of braking and fading. if you're keeping stock brakes, try fitting lightest wheel available which will fit the tire size you want. (usally smaller diameter wheels are lighter)

 

Bringing an old thread back to life here. Why do you think 15" wheels will make you slower on the straights? I would think the lighter weight would make you faster.

 

Maybe he's referring to the gearing change you would probalby see. There shouldn't be a dramatic difference. It would depend on the track, and the gear you were forced to run.

For example, if, with the 17's, you were at the top of 5th at the end of the straight, switching to 15's might force a shift to 6th, which could actually slow you down and cost you a couple mph. This is typically more of an issue with larger changes associated with a final drive swap, but everything has some effect.

Another factor is the slightly higher ride-height from the 17's - and the possibility that you might have to raise the suspension slightly to prevent rubbing.

 

I don't see that tire size would affect gearing or ride hieght.

If you use the "specified" tire size in 15, 16 or 17, the diamater of the tires is with in .25 inches.

JD

 

"specified" sizes are meaningless. It's not like anyone's going to be running 175/65/15 tire on the track... even if they could get decent tires in that size.

Personally, I'd be looking at:

225/45/15 - 22.8" OD
225/45/17 - 24.6" OD

Yes, you can buy a 225/55/15 with a 24.5" OD, but why? The only reason is to try to preserve a factory gear ratio which is too high to begin with. So... in effect (for me personally) there is a large diameter difference between the two sizes.

 

I have 205/50's and it certainly lowered the car a noticable amount.

 

I run 15's with 205/50 Kumho's. The smaller diameter does help lower the gearing coming out of the corners, only downside would be if you actually ran out of gear on a long straight in 6th or have a BBK. I have not come close to running out of gear yet.

I would be interested to see if there is any benefit to running a wider tire in thr R compound. From my expereince, a wider tire can and will slow the car down in the corners. 225 seems like alot of rubber for such a small car, esp if it is a race tire.

Anyone have concrete numbers between the two?

 

I run the 205/50 kumhos and love them.

Interestingly though... Smaller diameter isnt noticable when grouped with the CVT transmission. Atleast it doesnt feel that way. Do you think that the tranny computer has taken it into account?

 

Get some nice light 15s....I have SSR Comps in 15x7 with 205/50 SO3PPs for the track--they're really good for a street tire and if it rains you'll have a blast. Plus, your wheel bearings will thank you.

Gary