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      09-01-2015, 06:11 PM   #1
LDSM
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Tracking an m235 with PSS, what PSI should I aim for?

I've read some conflicting opinions on this. Most say you should aim for around 40psi hot, but others have suggested, since PSS tires have a soft shoulder and are prone to rolling over, the PSI should be upped to around 45-48 PSI.

So which one is it?
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      09-01-2015, 07:21 PM   #2
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try 44-46 all around hot start 38-40 cold else you will kill the shoulders

better start high and lower if you are not rolling over
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      09-02-2015, 05:07 PM   #3
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you really do not need that much pressure. The issue is more that the car has a lot of under steer in stock form. This makes it very easy to overdrive the car and push the front end causing the tires to roll. I know because I did it.

You would be better suited to listen to the tires and let up or increase the steering angle when the car washes out. I would say super sports in general run 38-40 hot. Any more and your changing the carcass shape quite a bit. this may cause the tire to roll over less, but at the expense of grip.
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      09-02-2015, 09:07 PM   #4
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Quote:
Originally Posted by Pparana View Post
you really do not need that much pressure. The issue is more that the car has a lot of under steer in stock form. This makes it very easy to overdrive the car and push the front end causing the tires to roll. I know because I did it.

You would be better suited to listen to the tires and let up or increase the steering angle when the car washes out. I would say super sports in general run 38-40 hot. Any more and your changing the carcass shape quite a bit. this may cause the tire to roll over less, but at the expense of grip.
M4 LCA FTW

I rather have less grip but still have tires at the end of the day
Although M4 LCA's and RE-71R are the real answer
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      09-02-2015, 09:10 PM   #5
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Quote:
Originally Posted by LDSM View Post
I've read some conflicting opinions on this. Most say you should aim for around 40psi hot, but others have suggested, since PSS tires have a soft shoulder and are prone to rolling over, the PSI should be upped to around 45-48 PSI.

So which one is it?
Let us know how it goes... take a picture before and after so you can compare of the sidewall
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      09-02-2015, 09:20 PM   #6
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I run a square set up and more camber than stock, so this info won't necessarily be good for a stock set up, but I start of at 32 cold front and 34 cold rear. Hot usually end up around 35 front and 36 rear.
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      09-04-2015, 02:54 AM   #7
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Quote:
Originally Posted by i8ur911 View Post
.....I start of at 32 cold front and 34 cold rear. Hot usually end up around 35 front and 36 rear.
+1 32F and 34R on my m135i with H&R springs and ARB's + M4 LCA's.

Works a treat even with stock size MPSS's
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      09-07-2015, 10:49 PM   #8
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Not sure if this will help but on RS-3 for autocross square setup (235/40/18) I am running 35/37 cold. Stock M235.
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      09-08-2015, 07:42 AM   #9
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Quote:
Originally Posted by pikcachu View Post
Let us know how it goes... take a picture before and after so you can compare of the sidewall
Thanks everyone for the advice here, I'll try to lower my psi a little more, next time out and see how it feels.

I didn't get a chance to take pics of the sidewalls. And I didn't adjust the psi too much. Based on the idrive display I was averaging around 38-39 in the front and 41-42 in the rear.

It felt pretty good in the corners and I didn't see much wear on the sidewalls. But then again, I wasn't pushing the car too hard, I was mostly concerned with keeping tire wear low more than absolute grip since I had to drive 3 hours home after the event.

I posted a video of some of the laps in the thread below if you want to check it out.

http://www.2addicts.com/forums/showthread.php?t=1170609
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      09-08-2015, 11:20 PM   #10
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On my 2015 M235i I have used hot temps around 38/42 F/R, although I'd be tempted to try a bit higher. My first set of PSS lasted 6 track days. The final day was 90+F and I was having to let air our thoughout the event, but the fronts were heavily corded on the outside shoulders by the end of the day.

I suspect with a bit of negative camber I would have gotten better wear (and better handling). Similarly, the rears had a lot of life left, so having a square setup would have allowed rotation and increased service life. However, that was before I had the LSD installed, and now the rears are getting more of a workout on corner exit. This week I'm having the Ground Control racing camber plates installed and I'm moving to a square setup with 18x8.5" Apex ARC8 ET38 wheels, so I'll be able to rotate the tires now. It should give me a bit less understeer, which should help with tire wear as well. And since I'm buying new wheels I am going ahead and moving over to 245/35 Hoosier R7s for the track...which will probably wear out even faster! My plan is to use the PSS as my wet track tire and the Hoosier as a dry tire.

In any case, the PSS are a blast on the track and had tons of grip, and other than the shoulder wear I don't have much to complain about. They could swing several PSI up or down and still perform, although I found the higher pressures seemed a bit more hooked up for me.

Last edited by politeskeptic; 09-08-2015 at 11:37 PM..
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      09-08-2015, 11:46 PM   #11
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Quote:
Originally Posted by politeskeptic View Post
On my 2015 M235i I have used hot temps around 38/42 F/R, although I'd be tempted to try a bit higher. My first set of PSS lasted 6 track days. The final day was 90+F and I was having to let air our thoughout the event, but the fronts were heavily corded on the outside shoulders by the end of the day.

I suspect with a bit of negative camber I would have gotten better wear (and better handling). Similarly, the rears had a lot of life left, so having a square setup would have allowed rotation and increased service life. However, that was before I had the LSD installed, and now the rears are getting more of a workout on corner exit. This week I'm having the Ground Control racing camber plates installed and I'm moving to a square setup with 18x8.5" Apex ARC8 ET38 wheels, so I'll be able to rotate the tires now. It should give me a bit less understeer, which should help with tire wear as well. And since I'm buying new wheels I am going ahead and moving over to 245/35 Hoosier R7s for the track...which will probably wear out even faster! My plan is to use the PSS as my wet track tire and the Hoosier as a dry tire.

In any case, the PSS are a blast on the track and had tons of grip, and other than the shoulder wear I don't have much to complain about. They could swing several PSI up or down and still perform, although I found the higher pressures seemed a bit more hooked up for me.
which events did you go to ?

I saw an EB at RTC a few weeks ago with corded from PSSs

Last edited by pikcachu; 09-09-2015 at 12:04 AM..
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      09-09-2015, 12:24 AM   #12
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Quote:
Originally Posted by pikcachu View Post
which events did you go to ?

I saw an EB at RTC a few weeks ago with corded from PSSs
That was probably me! I definitely had it over there a few weeks ago right after the tires went to cords but before the new PSSs went on. I've had some trouble getting the PSSs here in the Seattle area, so I had to wait for them to come in. Naturally I just ran over a screw yesterday, and it was the same story- Seattle BMW and Bellevue BMW didn't have them onsite, and even Tire Rack had a delay. How in the world my BMW dealership doesn't stock tires for a current model BMW is beyond me.
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      09-09-2015, 04:22 PM   #13
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Hot temperatures I usually aim for 36-37, I wouldn't let them go higher than 38 hot. To get these temps I would start out with a cold psi of around 31-32.
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