[midwestbmw]

Because I learned so much here to make the decision to get the car to track, wanted to share my experience to maybe aid someone else.

Road America
'18 M240ix
Prep: Motul 660, PFC08 pads front and rear, RE71s on non staggered 18x8 wheels.

Because of others saying understeer was an issue with the AWD, I went with higher tire pressure to prevent rollover, and even higher pressure in rears to help rotate. Best setup for me for the day:Cold: 38psi front, 41psi rear.

The higher pressure seemed to do the trick, didn't lose edges on the tires all day. (triangles still there)

Fantastic driving experience all day (except for some guy in an old GT40 not giving me a pointby for several laps ) Sport+ mode all day. Car rotated beautifully with trail braking, then just punch it after the apex. AWD system performed great on track. Is RWD better for track? Maybe...depends. But for a year round DD in snow country, this is the right car for me. (E.g., climbing an icy hill with RWD, even with snow tires)

Huge fan of the PFC 08's - strong braking all day, including at end of the 25 minute sessions. Brake temps stayed down with the help of the OEM brake ducts. Also, coming from Hawks, the amazing thing to me when changing them out was minimal pad wear, can likely use them for 4-5+ more track days.

[chattanooga240]

Good write up.

Stock rotors?

[khoa@x-ph.com]

Holiday done right!! Thank you for sharing your track experience OP.

[midwestbmw]

Originally Posted by chattanooga240

Good write up.

Stock rotors?

Yes, stock rotors. Very little wear showing after.

[msendit]

Originally Posted by midwestbmw

Best setup for me for the day:Cold: 38psi front, 41psi rear.

These are definitely too high, to the point of risking a blowout once you learn how to push the car harder. It's not uncommon to gain 10 psi when hot and 50 psi is pushing what these tires are rated for.

Unsolicited advice, don't worry too much about perceived understeer / tires rolling over / etc. at this point. Just focus on learning to push the car.

[BimBimM2]

Originally Posted by midwestbmw

Because I learned so much here to make the decision to get the car to track, wanted to share my experience to maybe aid someone else.

Road America
'18 M240ix
Prep: Motul 660, PFC08 pads front and rear, RE71s on non staggered 18x8 wheels.

Because of others saying understeer was an issue with the AWD, I went with higher tire pressure to prevent rollover, and even higher pressure in rears to help rotate. Best setup for me for the day:Cold: 38psi front, 41psi rear.

The higher pressure seemed to do the trick, didn't lose edges on the tires all day. (triangles still there)

Fantastic driving experience all day (except for some guy in an old GT40 not giving me a pointby for several laps ) Sport+ mode all day. Car rotated beautifully with trail braking, then just punch it after the apex. AWD system performed great on track. Is RWD better for track? Maybe...depends. But for a year round DD in snow country, this is the right car for me. (E.g., climbing an icy hill with RWD, even with snow tires)

Huge fan of the PFC 08's - strong braking all day, including at end of the 25 minute sessions. Brake temps stayed down with the help of the OEM brake ducts. Also, coming from Hawks, the amazing thing to me when changing them out was minimal pad wear, can likely use them for 4-5+ more track days.

Hello from Minnesota! The Twin Cities specifically

[TajoMan]

Originally Posted by msendit

These are definitely too high, to the point of risking a blowout once you learn how to push the car harder. It's not uncommon to gain 10 psi when hot and 50 psi is pushing what these tires are rated for.

Unsolicited advice, don't worry too much about perceived understeer / tires rolling over / etc. at this point. Just focus on learning to push the car.

Agree with the pressure.
38/41 cold is way too high for RE71r.
I would target 35~37 front, 33~35 rear when hot.
Rear still rotates nicely with brake. (square tire setup helps too)

BTW, I would love to go to the Road America someday. I heard that place is awesome.

[midwestbmw]

Originally Posted by msendit

These are definitely too high, to the point of risking a blowout once you learn how to push the car harder. It's not uncommon to gain 10 psi when hot and 50 psi is pushing what these tires are rated for.

Unsolicited advice, don't worry too much about perceived understeer / tires rolling over / etc. at this point. Just focus on learning to push the car.

I've been tracking RE71s for years, but thanks anyway.

The best way to get the inflation pressure correct for these tires is to use the sidewall markers (little triangles) to detect how far the tire is rolling over in corners. Decrease pressure if wear is not close to the markers (to let the tire rollover more) or increase pressure if wear is past the markers (to stiffen the tire and reduce rollover).

The pressures I gave just started nicking the triangles. So, IMO, for this car, (xdrive version), those pressures is where you want to be cold. Depending on track, of course Decrease pressure after sessions. Blowout a track tire ? Really ?

[TajoMan]

Originally Posted by midwestbmw

I've been tracking RE71s for years, but thanks anyway.

The best way to get the inflation pressure correct for these tires is to use the sidewall markers (little triangles) to detect how far the tire is rolling over in corners. Decrease pressure if wear is not close to the markers (to let the tire rollover more) or increase pressure if wear is past the markers (to stiffen the tire and reduce rollover).

The pressures I gave just started nicking the triangles. So, IMO, for this car, (xdrive version), those pressures is where you want to be cold. Depending on track, of course Decrease pressure after sessions. Blowout a track tire ? Really ?

You are the first one who uses that high pressure for RE71r that I know of.
I auto-crossed with RE71r and put 32~33psi in front and ~30psi in rear when hot.
It did wipe out the little triangle pretty quickly but the time was always faster with lower pressure.
(technically, the little triangle is not the indicator for sidewall roll. It can be used to judge rolling anyway)

I know the GTI folks uses fairly high pressure with RE71r for auto x and they put about 37~38psi in front when hot.
GTI has about the same weight in front axle as our car with same tire size.
That means we can put about the same pressure or less since the front tires would loaded little less in our car. (less longitudinal load with x drive)

Maybe, try lower pressure next time if you haven't tried.

[pikcachu]

Originally Posted by midwestbmw

I've been tracking RE71s for years, but thanks anyway.

The best way to get the inflation pressure correct for these tires is to use the sidewall markers (little triangles) to detect how far the tire is rolling over in corners. Decrease pressure if wear is not close to the markers (to let the tire rollover more) or increase pressure if wear is past the markers (to stiffen the tire and reduce rollover).

The pressures I gave just started nicking the triangles. So, IMO, for this car, (xdrive version), those pressures is where you want to be cold. Depending on track, of course Decrease pressure after sessions. Blowout a track tire ? Really ?

Problem with the xdrive is that you can't add camber easily so you have to run high PSI if you don't want to destroy the shoulders....

if you put the M2/3/4 LCA (rwd only) then you get about 1.8 neg camber and then you can run around 31 cold

and the best way to get tire pressure correct is with a pyrometer I'm pretty sure the center of your tire is the hottest part with such high psi but if you don't have a pyrometer using the triangle or some chalk is the best you can do

[MarcoZandrini]

the temperatures you need to be worried about are the the tires' temperatures after track time. A properly inflated tire will show very little wear on the sidewall. The last time I tracked my M240i at Virginia International Raceway (VIR), my instructor and I were very careful about tire pressures. We found the sweet spot for the Michelin's and there was almost no sidewall wear. Good choice on the PF08 pads. I could push my car as hard as I could and slam on the brakes and there was zero fade, lap after lap. They ain't cheap but I won't track my car without them.

[Maynard]

Originally Posted by MarcoZandrini

the temperatures you need to be worried about are the the tires' temperatures after track time. A properly inflated tire will show very little wear on the sidewall. The last time I tracked my M240i at Virginia International Raceway (VIR), my instructor and I were very careful about tire pressures. We found the sweet spot for the Michelin's and there was almost no sidewall wear. Good choice on the PF08 pads. I could push my car as hard as I could and slam on the brakes and there was zero fade, lap after lap. They ain't cheap but I won't track my car without them.

Curious what that sweet spot was for hot pressures?