Hey all what size wheel Tire combo do you find best for track and why?
I am currently running 205/40/ on 17x7 KoseiK1-TS
Is their any advantage to 16" rims?
Thanks
For your input
Kumpie

 

Can you can fit 16" over your BBK ? I can't

The Race Series at NASA requires 17x7 ", so stick with that

Phil

 

If I reduce the rotor size I can fit 16" on, just unsure of any advantage ? Thanks for your input, RU coming over for the cage and seat install this weekend?
Chili, big dogs and beer for the spectators?
Kumpie

 

The only real advantage to going to a smaller rim size would be comfort. When I went form my stock 15" rims on my MC to the 16" rims I have on there now I noticed the ride was a bit harsher. 205/50 R16's

 

No, I cannot make it, my daughter has 2 basketball games and a swim meet

Take pics and post detailed write-up please

Tell Super Chad I said HI !!!!

Good Luck,

Phil

 

Last outing at sebring 2 weeks ago.
I used 16" wheels with 205/45 -16 hoosiers 2:44.70 @ qualify 1
w/ 5 weekends on the tires
I tried 17" wheels with 225/40 -17 hoosiers 2:46.3 @ qualify 2
w/ 1 heat cycle on the tires
I raced with a fresher set of 16" and did 2:43.2 Race
w/ 3 weekends on the tires

For Sale 225/40 -17 Hoosier R-6 compound $219 each new, special
2 heat cycles $ 150 each..+ shipping SOLD

 

Can you say GEARING? :-)

 

Hi Pete! Long time no talk!

Minzilla,

I was going to reply the same. Whatever size you end up with, please make sure you take into account the effect on gearing!

 

And cost of the tire. Less material=less money.

 

Hello Dave,
I have been racing my Mini since Sept of 2003,started with with 215-40 17's on 17 x 7 1/2" rims...Won my first race using Pirelli's.
Soon swithched to 7x 15 wheels wheels w/ Hoosier 225/45/15's and have had good performance in BMWCCA club racing (D-Mod class) and previouslly in J-P. I am able to still use my Wilwood BBK's with them.
Guess I would have to go back to !7's if I decided to race with the USTCC class.
More Minis need to join BMWCCA racing, Octoberfest premier race will be in Texas this year. It would be great to have more Minis between the Beemers.
Regards,
Steve

 

ps:Forgot to mention that last April during the 2nd Phil Wicks event, first time ever at Sebring I tuned 2:35's flat finishing 5th overall with all the NASA cars(28 total) beh.ind twoo 997 Porsches, a Brumos 911 twin turbo 911 & a Ferrari 355 Challenge car. Not bad for the Mini.

 

You are obviously not stock like I am..Those are good times

 

Hello Alain! How are you? I have started to spend a little time on here, as I have a 2002 Mini Cooper at home, and I am about to add to it by buying a MCS.

What have you been up to?

Sorry for the thread jacking, btw....

 

After running 17" the last 2 years at BMW HPDE's I bought 15 X 7, Konig Rewinds with Hankook R-Compounds, 205-50-15. I seems that most of you are running 16 and 17" wheels. What immediate problems, differences should I expect? Speedo, etc. See the mods below in signature. Thanks

 

The only "problem" you'll face is how much quicker the car accelerates due to the smaller diameter.

I've been running 205/50/15 RA1s on 15x7 wheels and it is a great set up. I may switch to 225s in the future.

 

I have been racing with 15x7's for almost 4 years now. The tire choices are greater in the 225-45 15's or 225-50- 15's if you want to stay closer to the factory gearing. Yes, the smaller wheels have less rotational mass and will yield quicker acceleration.
They also look cool while lowering the car as well.

 

16 IN Will give you better gearing on your year car. Check your class and what you want to drive in. NASA requires 17.

 

I'm using 15x7 OZ Superleggeras on 225/50/15s. I went with this setup due to the larger tire choices available so I have pretty much tried them all sans the Hoosiers. Interesting to note, my friend has an '06 JCW with JCW suspension and because of the big-brakes he went with a 17x7 Superleggera with 205/40/17 wheel. The results on track were surprising with the lack of grip by comparision. My times in his car were 6 secs slower per lap. We are going to look into it further this season. I pulled an old email where we were discussing the weight differentials between the two setups, it's pretty interesting:

My current setup is this:
15" x 7" OZ Superleggera - 10lbs
225/50/15 Toyo RA1 - 23lbs
total weight - 33lbs
Actual tire width - 9.2"
Overall tire diameter - 23.0"

Shel/Ricky Option 2:
17" x 7" OZ Superleggera - 16lbs
205/40/17 Toyo RA1 - 19lbs -
total weight - 35lbs
Actual tire width - 8.5"
Overall tire diameter - 23.5"

I thought for sure his car would have been faster with the BBK he did have a rear swaybar. Needless to say he was pretty upset that his CN$50k MINI was getting it's pants handed to him...lol. My cars mods: 15% Pulley, Alta CAI, Invidia Exhaust, MTH, H-Sport Rear Sway Bar, Rear Control Arms, Camber Plates, H-Sport Springs, Custom shocks (stock shocks revalved for 40% stiffer on bump & rebound). Performance Friction 97 Front Pads (stock rotors).

Amit

 

DJAFACTOR
I would think your suspension difference's have alot do do with it. Plus who's the better driver???????

 

After Steve's ABS failure at Summit point, I was able to catch up to him for a little bit. I was surprised to see no difference in cornering speed between us (I was running 205/40/17 RA1s, Steve was on his 15" Hoosiers). This may have been due to the fact that Hoosiers are slower towards the end of races, but I was quite impressed with the performance of my RA1s.

What size were you running Steve?

-Brian

 

The suspension differences need to be taken into account however the braking performance probably makes up for some of it. My buddy is a great driver with tons of racing experience, porsche cup, formula ford, etc. We did swap cars and the results were the same. I'm putting the stock struts back on this weekend as 40% stiffer is too much for our downtown montreal streets. We are going to try 20% this summer.

Amit

 

The 17 x 7 OZ Superleggera weigh 14.2 lbs . . . at least that what mine weight and the 205/40/17 have a tread width of 7". A shaved RA1 (4/32) has a diameter of 23.2 in. Also, the 205/40/17 RA1 is a special reinforced tire. It is substantially lighter than similar Toyos and is not a good tire for this comparison because it only weights 19 lbs. If 'Ricky" ran a 215 instead, he would add +4 lbs per tire.

. . .and you, djafactor, could try a 225/45/15 Hoosier . . . 19.8 lbs but I think you need a wider wheel. Tread width is 9".

-----------------

As a rule of thumb (with all other factors being the same) . . . the smaller and lighter the wheel the better. Less centrifugal mass means faster accleration and quicker braking. It also means better turn in and thus, better handling.

Newton's second law of motion . . .

"The more mass the object has, the more inclined it is to resist any change in its motion."

The trend to bigger wheels is all about looks . . . not performance. Smaller diameter wheels mean lighter tires as well. The benefits of running the smaller wheel can be substantial.

I think this accounts for much of the difference in the lap times you discussed. Your benefit is not only lower weight . . . it's also the 'moment' of the weight. Your weight is closer to the center and requires less energy to accelerate or to stop.

Example: Swing a ball on a string above your head . . . the longer the string, the more force it takes to swing it, even though the ball weights the same.

The only real reason to run a larger diameter wheel is brake size and cooling (maybe looks ?). But, some of the benefits of larger brakes is reduced by the extra force it takes to slow down the larger rotational mass and weight.

Can anybody say . . ."inboard brakes"? . . . that would be nice, small wheels, big brakes.

Lastly . . . remember, there are 4 tires on the car. Most of the benefit is in the drive train but the lower weight at the rear is a benefit too. The same laws of physics apply to the rear wheels.

My 2 cents . . .

Randy

 

Very nice explanation Randy.