My first event in the Mini is next weekend. I'm running an '06 MCS with 16X6.5 Rota Slipstreams wrapped with 215/40X16 Kuhmo V710's. I'm on stock suspension and alignment for now.

I've run 710's on other cars (both 205 and 225/50X15) and run pressures in the upper 40's to low 50's.

I like to get the wisdom of experienced Mini autoxer's to get a starting point for next weekend. The lot is asphalt and I expect the temperature to be 40-ish.

Ray
#42 GS
BRR-SCCA

 

I would recommend as a starting point to pick up the latest issue of Grassroots Motorsports. Per has an excellent write up on his mini that applies very well to the MCS. It has alignment settings, tire pressures, front swaybar (which is heavily debated), and pretty much anything else you want to know. I sure wish I would have had that last year at this time when I picked up my Mini. Nice write up, Per!

Jake

 

GRM was in the mailbox when I got home from work.

Ray

 

You've definitely run the pressures too high in the past. 36-38psi on the front. The rear simply depends on what you want the rear to do, but any more than 40psi should get you tons of rotation.

For me, 1/16" toe-out in front, 1/16" toe-IN in the rear.

Brian

 

Old thread...but Brian, you run your pressures that low w/ the 710s? Mine do *not* like it that low. Lots of growling, loss of transitional grip without that much of an increase in sweeper grip.

Per

 

We may have gone as high as 40, but not likely, it was always in the high 30's. They didn't roll over too far and gave us the best readings without the centers being hot. We also saw a big difference in grip, particularly when cold. We kept the temperatures below 100 degrees as much as possible as well.
I'm no longer in a position to prove otherwise. I'm pretty sure other people ran higher though. Maybe I would've finished higher with higher pressures

Perhaps there's different builds that behaved differently?

Brian

 

FWIW, I run my Michelin Pilot Sport Cups are 32 in front and 30 in the rear... grip is nuts at these pressures and MUCH worse at 35+. Of course, my car isn't setup like a stocker, either (camber plates, etc.).

I guess the 710's have a softer sidewall?

 

Nope, they're pretty stiff, although they lose some transitional response at lower pressures.

Interesting stuff!
Per

 

Yeah, good to know about the V710's because those may be my next tires... if I get behind in the season points chase, that is... This year, I'll be running with the e36 and e46 M3's, M coupes and M roadsters with our local BMWCCA chapter - so I may need a bit more help!

The Michelin PSC's just seem to last a LOT longer on the very rough asphalt surface at our venue - a full season vs. 4 events with Hoosiers or V710's. There's no denying the V710's and Hoosiers are stickier, but I have a hard time selling the wifey on 2 sets of tires a season...

 

Just two? Try that with a co-driver who's addicted to autocrossing!

Per

 

I'm running 215/45/16's on the stock 16" wheels. Tire pressures are very subjective to your driving style and the tire. I have the Azenis Sport 215's. They have a wear marking on the side wall. It's just a little triangle that points out toward the tread. I start my pressures at 44 FR and 42 RR. I also mark the side walls with chalk to check the roll over. If the chalk is being taken off to the triangle I'll add some air, if it's not, I'll let out 1 pound at a time until it's right on the mark. They go up each run as the heat builds up so you will have to adjust them after each run. Take your valve caps off an put them in your pocket. Keep more air in the fronts than the rear and keep the pressures balanced left to right. I like a 2 pound difference between FR and RR for good turn in. At these pressures the RR will 'step' out a little on command by suddenly letting off the gas while turning. It takes some getting used to and at my first autoX this year last weekend I did complete 360 degree spin on cold tires. Have fun!!!

 

Depends on the tool you are measuring with. I ran mine at 36/42 most of the time on dry hot days with pretty good results. I always tell people to check my tire with thier gauge, just in case of a variance. It was nice meeting you at Nationals this year Per. I'm still thinking about that cone on day two...
Tony Savini

 

What would be the typical tire pressure difference to be used between a textured concrete surface and a very smooth asphalt surface?

 

3-5psi higher on concrete. But that doesn't always apply, you generally have to drive on it first or talk to people that have. Sometimes concrete can be low grip, but usually it's significantly higher.

Brian

 

Good result this weekend Brian. I guess it does not matter what you drive, you are fast. And quite the pax index placing.

I'll add to the thread saying that to get a MCS to rotate on concrete, you may have to run pressures significantly higher than 40psi. We made a break through discovery at Atwater regarding balance and rotation without compromising mechanical grip.

I don't want to give all the secrets away though, so I'll just say don't be afraid to experiment with high rear pressures. especially at places like Denver and Wendover.

Bones