Track tire pressure question, Michelin vrs. Conti

[///ACS330Ci]

Have any of you track guys switched from Conti's to Michelins and found you needed to make notable changes in your tire pressures?

I just replaced my Conti Contact 2's with Michelin Pilot Sport PS2 tires. I took them to the Nürburgring Nordschleife for the first time yesterday and they were sliding around quite a bit with the same pressures as what I used with the Conti's. Not snap and bite you kind of slides, but gradual four wheel drifts that seem to happen at lower corner speeds than the Conti's which I really didn't expect with the softer Michelins. The problem is they kept pushing me wide on my exits. The rubber didn't ball up as much as on the Conti's which is a good thing, but I need more mid-corner grip. Any thoughts?

[tatawaki]

if they're brand new, they may need to be worked in a bit. all tires will be different in regards to pressure, I went from 36psi on Toyo's to 41psi on Yoko's.

I mark my tires with shoe polish ( where the tread meets the side wall ) make sure you get the whole side tread, do a run, and if your scrubbing too much past the tread (onto the sidewall) then up the pressure.

[///ACS330Ci]

You have a good point ... I probably need to heat cycle them a few more times before I worry about tire pressures. The shoe polish is a good idea too

Thanks

[BMW Club Racer]

First to ask, What tire pressures do you normally use? Depending on how long the track session is, you should be starting out somewhere around 35 psi that way when the tire reaches operating temperature and the tire pressure builds up you will be at 40-42 psi.

The Michelin Pilot Sport 2 has a much better initial turn in then the Original Pilot Sport and the Conti Sport Contact 2's.

As was said in a previous post, you probably need to heat cycle the tires a few times before they work better. New tires are always slippery until they have been heat cycled a few times.

If you are losing mid corner grip, you may either be early apexing or just carrying a little bit too much entry speed.

[GMGBMW]

street tires belong on the street and not on the track....
step up and get some pilot sport cups And you wont have to worry about conti's sliding around.. The pilot sport 2 is a much stickier and more technologically advanced tire then the conti.

[///ACS330Ci]

Originally Posted by BMW Club Racer

First to ask, What tire pressures do you normally use? Depending on how long the track session is, you should be starting out somewhere around 35 psi that way when the tire reaches operating temperature and the tire pressure builds up you will be at 40-42 psi.

39 psi front / 37 psi rear cold with 19"s. These pressures worked very well with the Conti Contact 2's. I can check the Michelin Pilot Sport PS2 hot pressures at the Nordschleife this weekend as long as the rain holds off. The tires were definitely getting enough heat in them the last time though as the tires were much hotter to the touch than the Conti Contact 2's. The Michelin's rubber din't seem to ball up as much as the Conti's though

Originally Posted by BMW Club Racer

The Michelin Pilot Sport 2 has a much better initial turn in then the Original Pilot Sport and the Conti Sport Contact 2's.

I agree that the PS2 is a much better tire than the Pilot Sport, but I still haven't made up my mind as far as how it compares to the Contact 2's. Up to this point I've turned quicker laps on the Conti's, but we'll see. I think the Michelin's have a much softer compound rubber so if I can sort everything out out they should have a lot more to offer.

Originally Posted by BMW Club Racer

As was said in a previous post, you probably need to heat cycle the tires a few times before they work better. New tires are always slippery until they have been heat cycled a few times.

I've heard conflicting information about this from the experts when it comes to "street" tires, but I tend to agree with you. I've put them through a few more heat cycles and they seem to be getting better already but I haven't had the car back to the track yet to see for sure.

Originally Posted by BMW Club Racer

If you are losing mid corner grip, you may either be early apexing or just carrying a little bit too much entry speed.

Maybe, but that wouldn't explain why the Michelin's are sliding more than the Conti's. BTW, I posted one of my laps online if you'd like to see it - My Video Lap Feel free to offer any inputs to me if you like. Bear in mind this is a street car (daily driver) on street tires (this lap is on the Conti's).

[///ACS330Ci]

Originally Posted by GMGBMW

street tires belong on the street and not on the track....
step up and get some pilot sport cups And you wont have to worry about conti's sliding around.. The pilot sport 2 is a much stickier and more technologically advanced tire then the conti.

LOL, don't I wish I could! Then again I wish I had a dedicated Ring car

I've done a few laps in a e46 M3 CSL running Cups and the thing stuck like it was on rails

[///ACS330Ci]

Originally Posted by BMW Club Racer

First to ask, What tire pressures do you normally use? Depending on how long the track session is, you should be starting out somewhere around 35 psi that way when the tire reaches operating temperature and the tire pressure builds up you will be at 40-42 psi.

OK, it was a bit cooler this past weekend up in Nürburg with overcast skys for most of the time, but I got in some laps paying particular attention to how the tires reacted. In the first half of the lap (1-lap is about 13 miles btw) they where pretty darn good, half way on they started sliding earlier and earlier and I found I had to wait longer and longer to get back on the throttle. When I was able to get parked and check hot pressures, all four corners were within 43-44 psi. Too high, even with 19's?

[BMW Club Racer]

Its possible that those hot pressures are just a couple psi too high, however I'm thinking that you might just be cooking the tires. You should get a pyrometer and check your tire temperatures. On that track, the tire temperatures must get really high with laps being that long. If your tire temperatures are going over the 140 degree mark you are just going to be sliding around after that point. Street tires start to lose grip with much higher temperatures then that. If the temperatures are getting that hot, then you are pushing the tires too hard and need to back off a little to keep the tire temperatures lower.

[///ACS330Ci]

Correct me if I'm wrong, but doesn't running a lower pressure increase temperature?

[///ACS330Ci]

Also, won't the unshaved tread depth cause the temperature to rise because the tire is moving around more?

Maybe I should just get another set of rims and put some Pilot Sport Cups on 'em. Like I have the money for that

[BMW Club Racer]

Originally Posted by ///ACS330Ci

Correct me if I'm wrong, but doesn't running a lower pressure increase temperature?

You are correct. However you still need to take into consideration the tire pressure increase. If your tire pressure increases by 6-8 psi when hot, and you want the tire pressure to be around 40-42 psi, you need to start at a lower pressure tire pressure when cold, so the tires will reach the correct tire pressure when hot.

[BMW Club Racer]

Originally Posted by ///ACS330Ci

Also, won't the unshaved tread depth cause the temperature to rise because the tire is moving around more?

Maybe I should just get another set of rims and put some Pilot Sport Cups on 'em. Like I have the money for that

Yes, the tread blocks on a street tire will move around causing the temperature to increase, however you need to take the fact that they are street tires into consideration and only drive at the limit of the tires, even if the capability of the car is more then the tires.

Another set of Wheels with Track Tires would be the way to go! I do think though that since this is your daily driver, you should stay on street tires, unless you really feel the urge to go that much faster on the course. Learning the street tires more will only help you become a better driver on the street in an emergency situation. It takes a certain finess to drive race tires at their limit, as to where street tires are more forgiving.

[///ACS330Ci]

Originally Posted by BMW Club Racer

It takes a certain finess to drive race tires at their limit, as to where street tires are more forgiving.

Good advice, but I've been doing trackdays for 12+ years and have had the opertunity to even drive on race slicks in the past (although not with this car)

BTW, quick little update. Yesterday I went back to the Ring to do a little more testing. I dropped 2 psi from all four corners and the tires did much better I was actually surprised how much better, even after two laps in quick succession they were sliding much less. Next time I think I'll drop them 1 more psi and they should be just about there. Then I'll just have to regain my confidence with them.