I am looking to get some some very light wheels like Kosei K1 Racing wheels as they are fairly inexpensive and very light. TireRack seems to have them in only 15x7 (et 25, 30, 38) or 15x8 (et 35). Can anybody suggest the specs of the wheels which would work for my 07' Cooper S as far as clearance issues and what size tires should I be running on these?

Thank you,
KK.

 

I run the K1s at +38.

I would expect the 205/50-15 wouldn't give you any trouble.

I'm running 225/45-15 at present, and on the back axle the outer edge of the tire does interfere slightly with the inner fender liner over the bumps.

Please note that I am NOT running the OEM suspension - hopefully someone will chime in here that is.

My setup offers both plus and minus for fitment - the minus includes quite a drop, and the plus includes a fair bit of camber up front.

The +38 is of course 10 mm less offset than stock, so I'd expect any issues to occur at the outer edge of the tread, not at the inner edge.

Cheers,

Charlie

 

Thank you for the response. Do you see any advantage on going to the 15's from 17's and running 225 wide tires? I assume I don't really have to worry about hitting the fenders as this would just be for AutoX setup.

 

the only advantage I'm aware of is the mechanical advantage which arises from a lower tire diameter - and that is a two sided coin

my race setup is 23.9" of diameter, which is a 4% reduction from stock.

since the radius is reduced, the engine has a slight improvement in leverage with respect to the contact patch, increasing the thrust available by 4% - that translates into 8 additional hp in my car.

the down side is that 2nd gear now provides 4% less speed at red line - whether that matters depends on the course. I've the JCW red line on my car, and have only hit the limiter twice in six years of competition.

With respect to the 225 versus 205 question, in my experience it's very close, and with my 7" wide rims it may be a wash... Were I running 15x8 at +42 I might feel differently.

I've run the 225 Hankook RS3 one year, and the Toyo R1R at 225 also, and at this moment I am ditching the latter and returning to the 205 Direzza.

Just one data point though, so take me with a grain of salt please.

Kind regards,

Charlie

Ps: I'm not sure that I would agree about rubbing not being an issue - even if the wheel/tire combination is only used for autocross.

 

I don't have experience with either wheel diameter, but you might also consider 16" wheels. At an AX yesterday I saw a stack of wheels/tires for sale that were used last year by the driver who mopped-up BRR-SCCA D Stock in a borrowed/rented MCS. He won class every event and also made the top 5 in PAX times almost every event.

The wheels are 6.5X16" (to be stock class legal) Rota Slipstreams (ET 45, white, 13# each). The tires were Kumho V710 in size 215/40/16. Those tires are about 1.8" smaller in diameter than the 195/55/16 OE tire that comes with the OE 6.5X16" wheel (22.6" versus 24.4"), but it seemed to work well for him.

 

Charlie, I notice you have a 2004, while the OP has a 2007. I thought that the 'S' brakes on the second-gen cars were the same as the JCW brakes on the first-gen cars, and won't work with very many 15" wheels (or even some 16" wheels.)

 

Link to Scca solo build up of 2008 Cooper S by former nat'l champ
Craig Wilcox.
https://www.facebook.com/pages/Mini-...1980375?v=wall

 

Oh mercy! I didn't ask what CLASS the Op intended to run in. Thanks for catching that folks. Obviously I am not running Stock.

Cheers,

Charlie

 

Charlie: Since the OP asked about 15" wheels for his MCS, I don't think he's planning to run stock either. He also asked about wider than OE 17" wheels and tires in another post. Thus, I think your posts are quite relevant.

 

mebbe, but i need to read much more carefully. IIRC one must be careful with 15" rims with respect to brake clearance in some cases with the Gen 2... possibly that's only with the JCW though.

"post in haste, regret at leisure"

 

I run O.Z. Ultraleggera 16" (x7, 37mm offset, 15 lbs) with Bridgestone Potenza RE-11 205/45R16 (same width/aspect ratio as the stock 17"). I just mount them with no spacer and there is absolutely no interference at all. I run SCCA solo (Road Tire class) and they are very competitive. I ran Kumho Ecsta XS last year and they were phenomenal in the dry. The RE-11s aren't quite as sticky as the Ecstas in the dry, but they are close, and they beat them hands down in the wet, and we get a lot of rain

 

Welcome to NAM, dananotech.

Nice 1st post too.

 

Thanks! Great site! Glad I found it.

For KK: btw, mine is a 2008 S Convertible with sport package and limited slip diff. I have done nothing to it except the wheels & tires. It is a blast to autocross with it! Have fun!

 

Thanks a lot for all the inputs guys!

KK.