I'll be taking my 03 MCS to the track for the first time next month at Lime Rock, CT for a BMWCCA driver's school. I'm not a novice, but it's my first time in the Mini, which is shof with 205/45x17 Toyos on 7.5" wide alloys. I'm seeking guidance as to a starting point on tire pressures.

 

Which Toyos? What mods to the suspension?

 

Suspension mods: New Koni yellow with stock springs all 4 corners. New Powerflex polyurethane front control arm bushings w/sport option (retainers), M7 upper stress bar (no camber adjusters), 21 mm rear sway bar set at middle setting. Remainder of suspension is stock and in good condition.

Oops. Tires are not Toyo. They are Yokohama AVS ES100 with about 1/2-1/3 of tread remaining.

Other recent mods include Hawk HP brakes on plain rotors, SS brake lines, TSX engine torque stabilizer. Original owner had added 15% supercharger pulley, light Al flywheel w/stage 2 clutch, cold plugs w/Nology wires, remapped accordingly (or so I was told), and had added the 21 mm rear sway bar.

And ~116,000 miles. I bought it at 113,600.

 

These are suggestions only. I've never driven Lime Rock.

Start with your fronts at 36 psi cold, rears 32 psi cold. Be gentle on your warm up lap and once warm, pay attention to understeer and if the back end is loose or not.

At the end of your first session, look at the tire tread to see if you are rolling onto the sidewall. Also check for your hot tire pressure. The car will tell you what it likes, you just need to know how to "listen". I've no experience with your specific tire so I don't know what the hot pressure should be ideally.

 

wow, that seems REALLY high to me. Granted, I'm on R compounds but I run 33 psi HOT at the track. With pressures that high it seems like he'd be sliding all over the place.

 

I'm surprised that they are that low. I run 34 all around on the street, Guess I'll bring the chaulk along and hope I don't shed some chunks before the end of the 1st session.

 

Be careful of the tires you are using. Those Yokis get old fast, and it has nothing to do with tread. If they are two years old they are most likely hard and just won't stick real well.

The question should not be what pressure to start with, but rather what it should be hot. Starting pressure to obtain your goal in hot pressure depends on a few things. Ambient track and air temps, suspension setups and how hard you run are the most prevalent in a street car at an HPDE.
I would say that your hot pressure should be about 32-34. If it's a warm day I might start at about 28-29 psi. Remember to take pressure at the end of each session. You'll find that the left front and left rear are about 1-3 psi higher then the rights at LRP. Balance out the pressure right then so all tires match.
Then the next run start to feel what's going on. To much oversteer, understeer? Then add a little or remove a little from the rears.

Be safe.

 

I run Yokohama AVS ES100 and have no camber adjustment in front. I've run on the track as high as 40psi all around, and the side walls still get chewed up. I think that not having front camber adjustment dictates having fairly high tire pressures.

Edit: just to be complete I'll add that I am running 16" wheels

 

I would assume that that's also related to how noisy the darned tires are. I'll be happy when they're scrubbed bald and I can get a new set.

I guess I'm too used to a heavier car, having run a 535i at LRP for several years. Anything less thn 40 hot would have been rolling onto the sidewall. Even the Jetta GLI I ran before that was happiest around 38 front, 35 rear hot. I'm surprised at the low recommendations.

I'll start around 29-30 and see where it goes; I'm sure the track will be cool on a May morning. I'll be taking it easy for the first set anyway to get used to the new-to-me car. Thanks for the advice.

 

True about the camber plate, or non camber plate problem. I never tracked a Mini without them so I guess I need to be careful on my advice. I know the Mini eats front tires in a single day sometimes.

 

I should have put on a caveat to my earlier post - my car has all stock suspension. My "track" tires are RT615s. If you have Rcomp tires, or modded suspension, you will need to do things differently. Hence I say these are only suggestions. Best advice comes from someone with a setup similar to you and has also driven the same track. Good luck and let us know how it goes!

 

I've added polyurethane front control arm bushings, and Konis on stock springsand the car came with a heavy rear sway bar. Otherwise the suspension is stock. The tires are street tires, not Rs.

 

With the tires you are running go with at least 34 front. Rears will depend on how that 22mm sway bar handles. Probably wil need to run about the same to keep the car neutral.

 

I think 34 front is a decent starting pointif that's the HOT pressure. I tracked with my street tires before (the stock runflats) and found 35 psi to be around the upper limit, hot. Cold, I'd start around 28 psi front, 31-32psi rear. The fronts will heat up a lot more than the rears.

 

for those of you that plan on doing more than 3 events a year i recommend a second set of wheels with the tires. Get the cheapest tires you can find for your track tires. you will ruin tires when your learning how to do this. the MINI handles great and you can ride it's coat tails for a while at the expense of eatting up tires. Also be sure to rotate the tires so the front left gets a break.

cheap tires= $80
R-comp tires= $160-$220

benefit of R-comp when you are leaning the car is you'll hit the wall 20mph faster than if you were using cheap tires.

 

Man, am I happy to have found this thread tonight.

'07 MCS w/JCW tuning/aero/suspension, Nitto NT01 205/40/17 on 17x7 ASA JH6 lightweight wheels,

Running at Pocono last week, I had the following tire pressures:

Cold: front 34, rear 32

Run 1: RF40, LF41, RR37, LR38
Run 2: RF42, LF44, RR38, LR40
Run 3: RF43, LF44, RR39, LR40
Run 4: RF44, LF45, RR39, LR41

Air temp: high 70's/sunny

She was definitely understeering during the last couple of runs... mushy in the hairpins. Judging by this thread, I was way overpressure, right? I'm new to this so I really appreciate the help.

 

After your first run you should have immediately set both fronts the same, ... maybe 40, and the rears the same at maybe 40 also. Then take it from there.

All in all, all of this stuff is pretty much guess work without a pyrometer and mfg recomendations.

 

Cheep tires, one, maybe two days at the track and shot, x however many track days.
Toyo RA1s or R888s, maybe 10+ days at the track.
Ummm, I would have to really disagree with above post on cheep tire reomendations.

 

Thanks for the advice. Is 40 too high? Should the hot pressures be in the mid-30s per your post, above?

 

It just so depends on the tires. The Nitto NT01 seem to be happy at 39-40 hot. FWD cars tend to like a bit more pressure then RWD cars.

So, yea, I think 40 hot is a good place to start with these particular tires.

When your doing a track day place a strip of wide masking tape on the fenders, over each wheel well. On this tape write down all your tire pressure info for the day. Write down cold starting pressure. Make note of ambient weather temps. Come in right after a run and write down hot temp. Adjust if you need and write those #s down and so on and so on. Make a log and keep all this info. Very useful.

 

sled, i'm alright with not agreeing about the cheap tires. I like the idea of masking tape on the fenders. I've been using NT01's the past few months. I've been starting cold at 30-31 and getting up to 38 all the way around with good results.

here are some of the reasons for my cheap tire remarks.

i've got a buddy with an STI that eats tires on the track. He decided to start using cheap tires because he only gets a few days out of them R-cmpd or cheap. He also has and elise he tracks but uses the sti for rainy days or tracks far away he has more than a few hour drive.

I had a student at VIR in a MINI that was runnnig stock tires and wouldn't bump up the tires a few lbs per my suggetion and we kept spinning in hogpen. His response was that he obviously needed stickier tires and that he was going to get them for his next track event. That was his first event now he's off on R-cmpd for his next one. not a good idea.

 

i have to agree w/ onasled on this one. to get one event out of a set of "cheap" tires is optimistic. if you are getting more than this, you aren't driving hard enough. tire recommendations are as dependent on the driver as they are on the car. i used to be able to run street tires for more than a weekend.....no more. it cost stupid $$ to track a car. don't skimp on the rubber.

 

Lots of good wisdom here. For my Nitto NT01s, I'll go with 31-32 at cold temp all the way around, and then adjust each tire up or down to get 39-40 at hot all the way around as the day progresses. For starters.

What should I expect with overinflation? Underinflation? What kind of adjustment increment once I decide that I need to go up or down? Should I bring them all up or down together or just fronts/rears? Did you eventually end up running asymmetrical pressures once you knew what you were doing?

I appreciate the info. Thanks again

 

Tire pressure is a black magic. my first step would be tire roll. if your getting below the tire wear marker on the edge of the tire you need to add air or slow down in turns. Most tire wear markers are a small arrow on the edge of the tire or even a "tw" on the sidewall. you want to just reach the tip of the mark. The next step for me...... would be tire temps. that is best done on the pit lane during hot laps, not after a cool down lap and a few trips around the paddock. what you would like to see with your temps is a nice liniear line. such as: x, x+3, x+6 not x, x+5, x. that would mean your over inflatted. in a perfect world you would have x,x,x but you can only do that if you have no camber and don't turn so don't expect it. Again tire pressure is a black magic. There is the possibility your not drving your car hard enough to get the tires up to temp.

please have your own tire gauge. always use the same tire gauge. there are small differences in most tire gauges and if your using more than one your screwd when it comes to consistency.

the current set of Nittos i'm on have worn really well. i rotate them often front to back and all the way around. This set has seen 4 tracks. the most recent ones short tracks, 2-2.5 miles with no long straights. i've been starting the days at 31 and checking them after 15 mins of hot laps and gonig back out. I like 38 on these busy courses with not big straights. i've found that as the day gets hotter i'll have a little to much pressure. my tires will skip and studder with understeer. just taking out a half a lb fixed it.

not to blow my horn but last year i did over 40 track days. this year i'm on schedule to do the same amount not including work or 1 lap of america.

so far VIR 8 days, CMP 6 days and Barber 4 days.

 

FYI

I have 615s and I run 40 - 42 in the fronts and 35 -38 rear depending on outside temp and course conditions on an 05' Cooper with Hotchkis sport springs stock shocks and h-sport lower control arms and Helix camber plates.

My settings are -2.0 deg camber with 1/16" toe out front -1.5 deg camber with 1/16" toe in rear.

The car can be set from understeer to oversteer with rear tire pressure alone.

I'm not the best at autoxing but after a year of it I'm consistantly scoring in the 950s in pax.

Durring a track day at the local road course I checked my tires with a pyrometer and found that the outside edges were hottest and the inside the coolest which suggests I need more front camber. I can't add any more front camber until I install coilovers because the springs will hit the inside of the wheel well. Doe's any one know at what point of neg camber do you start to seriously lose braking power? I'm not that concerened about it for autox (cause I rarely use the brakes) but more for road courses.