THE LARGEST BMW 2-SERIES FORUM ON THE PLANET
2Addicts
2Addicts
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
2Addicts | BMW 2-Series forum Technical Topics Tracking / Autocrossing Any autocross advice for the M235i?

Post Reply
 
Thread Tools Search this Thread
      04-24-2018, 12:25 PM   #67
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by gp_solo2 View Post
To be honest there is more variables than just weight and diameter since a saw the difference when switching back to my winter tires so different, width, tread design, conpound, diameter and weight and I agree that weight is not a major one here (but I know that going down to 17 inches will cut it and will be good for performance).

I will still do some additionnal research on internet but will likely try 245/40/17 RE71-R on 17x7.5 wheels this year. To me it looks like the most optimal setup for F-Street unless I find evidences that 225 would be better on 7.5 wide wheels.
Have you tried 245 tires?
how was it? Any issues?

I am think about going 223~235 on 17" rims all around for auto X.

It looks like there is only 0.1" thread width difference between 225 and 235 for most tires, but there is big jump from 235 to 245 in thread width.

If there is no issue with 245, I may try it. Otherwise, I will go with 225.
Appreciate 0
      04-24-2018, 01:21 PM   #68
gp_solo2
Enlisted Member
gp_solo2's Avatar
42
Rep
30
Posts

Drives: BMW M235i
Join Date: Jul 2015
Location: Mirabel, QC

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
Quote:
Originally Posted by gp_solo2 View Post
To be honest there is more variables than just weight and diameter since a saw the difference when switching back to my winter tires so different, width, tread design, conpound, diameter and weight and I agree that weight is not a major one here (but I know that going down to 17 inches will cut it and will be good for performance).

I will still do some additionnal research on internet but will likely try 245/40/17 RE71-R on 17x7.5 wheels this year. To me it looks like the most optimal setup for F-Street unless I find evidences that 225 would be better on 7.5 wide wheels.
Have you tried 245 tires?
how was it? Any issues?

I am think about going 223~235 on 17" rims all around for auto X.

It looks like there is only 0.1" thread width difference between 225 and 235 for most tires, but there is big jump from 235 to 245 in thread width.

If there is no issue with 245, I may try it. Otherwise, I will go with 225.
Quote:
Originally Posted by TajoMan View Post
Quote:
Originally Posted by gp_solo2 View Post
To be honest there is more variables than just weight and diameter since a saw the difference when switching back to my winter tires so different, width, tread design, conpound, diameter and weight and I agree that weight is not a major one here (but I know that going down to 17 inches will cut it and will be good for performance).

I will still do some additionnal research on internet but will likely try 245/40/17 RE71-R on 17x7.5 wheels this year. To me it looks like the most optimal setup for F-Street unless I find evidences that 225 would be better on 7.5 wide wheels.
Have you tried 245 tires?
how was it? Any issues?

I am think about going 223~235 on 17" rims all around for auto X.

It looks like there is only 0.1" thread width difference between 225 and 235 for most tires, but there is big jump from 235 to 245 in thread width.

If there is no issue with 245, I may try it. Otherwise, I will go with 225.
No I did not test finally. I went the opposite route instead and tried the 225 all around with the assumption that the thread width was similar to the 235 and overall diameter smaller thus a better acceleration. Hard to compare from one season to the other but I beleive the 235 was faster overall but less fun on the road.

If you can afford to test the 245 and return them if they don't fit I would definately try that.
Appreciate 0
      04-24-2018, 01:46 PM   #69
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by gp_solo2 View Post
No I did not test finally. I went the opposite route instead and tried the 225 all around with the assumption that the thread width was similar to the 235 and overall diameter smaller thus a better acceleration. Hard to compare from one season to the other but I beleive the 235 was faster overall but less fun on the road.

If you can afford to test the 245 and return them if they don't fit I would definately try that.
Most likely I will be going same route as you did.

How was RE71?
I heard that the sidewall is very stiff and I prefer stiff side wall for auto x.
Stock MPSS was like a jelly at 48 psi in front. lol
Appreciate 0
      04-24-2018, 03:11 PM   #70
gp_solo2
Enlisted Member
gp_solo2's Avatar
42
Rep
30
Posts

Drives: BMW M235i
Join Date: Jul 2015
Location: Mirabel, QC

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post

Most likely I will be going same route as you did.

How was RE71?
I heard that the sidewall is very stiff and I prefer stiff side wall for auto x.
Stock MPSS was like a jelly at 48 psi in front. lol
Yes sidewall is very stiff but not more than my run flat that came with the car. If I recall I was running 33psi front and 36 psi rear. I prefered the feel of the rear with higher pressure but lower was better for traction coming out of the turns.

Expect a noisy ride when the threads are mostly gone.
Appreciate 0
      04-24-2018, 03:16 PM   #71
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by gp_solo2 View Post
Yes sidewall is very stiff but not more than my run flat that came with the car. If I recall I was running 33psi front and 36 psi rear. I prefered the feel of the rear with higher pressure but lower was better for traction coming out of the turns.

Expect a noisy ride when the threads are mostly gone.
33 psi in front? wow
I was running 45~48 psig in front with MPSS.
It wore down to sidewall when I put 42 psi.
Appreciate 0
      04-24-2018, 03:31 PM   #72
gp_solo2
Enlisted Member
gp_solo2's Avatar
42
Rep
30
Posts

Drives: BMW M235i
Join Date: Jul 2015
Location: Mirabel, QC

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post

33 psi in front? wow
I was running 45~48 psig in front with MPSS.
It wore down to sidewall when I put 42 psi.
I never ran the MPSS but maybe the fact you were stagered made your car to push more?
Appreciate 0
      04-24-2018, 04:09 PM   #73
Dylan86
Lieutenant Colonel
Dylan86's Avatar
Canada
913
Rep
1,842
Posts

Drives: M235i MP Edition, 6MT
Join Date: Jan 2016
Location: Rossland, BC

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
33 psi in front? wow
I was running 45~48 psig in front with MPSS.
It wore down to sidewall when I put 42 psi.
WOW that's high, lol

I was starting my 20 minute sessions at 32-33psi and I'd be around 40psi hot (most cases higher) by the time I came back to the pit area, these tires heat up super fast.. I wouldn't run more than 38-40psi cold, for street use, let alone a scrub session... I suppose autoX could yield a higher starting pressure (I've never done autoX) since you need your desired tire pressure right away, as opposed to track where you can warm up a lap or two, first..
Appreciate 0
      04-24-2018, 04:15 PM   #74
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by Dylan86 View Post
WOW that's high, lol

I was starting my 20 minute sessions at 32-33psi and I'd be around 40psi hot (most cases higher) by the time I came back to the pit area, these tires heat up super fast.. I wouldn't run more than 38-40psi cold, for street use, let alone a scrub session... I suppose autoX could yield a higher starting pressure (I've never done autoX) since you need your desired tire pressure right away, as opposed to track where you can warm up a lap or two, first..
I guess it's my poor driving too.

I used to put 50 psi in front when I auto x my 07 GTI. lol

Tire does not heat up that much during auto x. You run for 1 minute and wait for 5~10 min.
The pressure goes up maybe 3~4 psi.

and of course, I lower it down to 35 psi for street use.
Appreciate 1
Dylan86913.00

      04-24-2018, 04:17 PM   #75
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by gp_solo2 View Post
I never ran the MPSS but maybe the fact you were stagered made your car to push more?
possibly.

I actually lowered the rear to 35 psi (stock is 39 psi).

I guess it's a combination of heavy front (it's almost 54:46 for x drive) and skinny tire with soft side wall.
Appreciate 0
      04-24-2018, 05:58 PM   #76
gp_solo2
Enlisted Member
gp_solo2's Avatar
42
Rep
30
Posts

Drives: BMW M235i
Join Date: Jul 2015
Location: Mirabel, QC

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
Quote:
Originally Posted by gp_solo2 View Post
I never ran the MPSS but maybe the fact you were stagered made your car to push more?
possibly.

I actually lowered the rear to 35 psi (stock is 39 psi).

I guess it's a combination of heavy front (it's almost 54:46 for x drive) and skinny tire with soft side wall.
Quote:
Originally Posted by TajoMan View Post

possibly.

I actually lowered the rear to 35 psi (stock is 39 psi).

I guess it's a combination of heavy front (it's almost 54:46 for x drive) and skinny tire with soft side wall.
Ok...mine is a RWD with square setup. xdrive may push a lot more from the front. What mode do you run? Sport plus or DSC Off?
Appreciate 0
      04-24-2018, 06:34 PM   #77
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by gp_solo2 View Post
Ok...mine is a RWD with square setup. xdrive may push a lot more from the front. What mode do you run? Sport plus or DSC Off?
DSC off

As long as I brake in straight line, it's not too bad.

So, it is like 70% on driver and 30% on the car. lol
Appreciate 0
      04-25-2018, 08:39 AM   #78
teinesina
New Member
3
Rep
28
Posts

Drives: M240xi
Join Date: Jan 2018
Location: Nevada

iTrader: (0)

RE71s, 33 cold, 37 hot. 235-40-18 square. Xdrive 8AT. Sport+ in manual mode, shifted to 2nd and left it there. I found that the car shifting for itself was way too abrupt and it always did it at the worst possible times. I have taken it to three autocross events and two track days. I am pretty much in love with this car and I think it is doing amazing. Iím coming from Mini and Iím still trying to get a feel for this car, but I think it is already doing great . I learned very quickly that you do not touch the gas in the corner on this car! It always seems to be in its power band, no waiting for boost. Takes off from the line like a bullet. I feel like itís just the right amount of power. We see people come in with 700 hp cars and it always looks like a struggle to control and you only need about a third of that power.
Appreciate 0
      04-25-2018, 09:26 AM   #79
teinesina
New Member
3
Rep
28
Posts

Drives: M240xi
Join Date: Jan 2018
Location: Nevada

iTrader: (0)

Quote:
Originally Posted by teinesina View Post
you only need about a third of that power.
OK, so maybe half is good. LOL
Appreciate 0
      04-25-2018, 10:42 AM   #80
cxp213
Lieutenant
cxp213's Avatar
277
Rep
554
Posts

Drives: M235i
Join Date: Apr 2017
Location: TX

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
How was RE71?
I heard that the sidewall is very stiff and I prefer stiff side wall for auto x.
Stock MPSS was like a jelly at 48 psi in front. lol
RE-71Rs (and Rival S 1.5) are one of the best, legal street tires you can get that's still reasonable in price (unlike Sport Cups). There's a reason why many people run these tires at national level events.

Your pressures are WAY too high. You need to be in the mid 30s if you want grip. Given that these tires have stiff sidewall, you don't need to run as high of pressure.

Quote:
Originally Posted by TajoMan View Post
I guess it's my poor driving too.

I used to put 50 psi in front when I auto x my 07 GTI. lol

Tire does not heat up that much during auto x. You run for 1 minute and wait for 5~10 min.
The pressure goes up maybe 3~4 psi.

and of course, I lower it down to 35 psi for street use.
Tires definitely heat up (although not as much as a track session) and it's a little more than 3-4 psi if you're pushing the car enough and the tires are sticky. The interval between your runs varies by club, but you actually need to be constantly checking/adjusting your pressure before/after each run until about your 4th run or so.

Get some chalk and mark your tires from the edge of shoulder tread block to the sidewall, so you can see how much rollover you're getting (will vary based on tires, camber, psi, etc). Then find the tread marker on the sidewall of the tire to see where the rollover needs to stop ideally. From there, you just adjust tire pressure and camber as appropriate. Having a pyrometer helps but I wouldn't worry about that now. Of course, if you don't have enough seat time, none of this should be your primary concern, but that's another point.

BTW, for FWD, you want more pressure in the rear so you can get the rear to rotate easier. By adding pressure (and that much at that) to the front, all you're doing is introducing more understeer.

No offense, but I think you need to start making friends at your local autocross who is national level or very competitive locally, because I get the feeling you're doing things without proper guidance or someone's feeding you bad advice.

What clubs are you racing with in Chicago?
Appreciate 0
      04-25-2018, 11:07 AM   #81
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by cxp213 View Post
RE-71Rs (and Rival S 1.5) are one of the best, legal street tires you can get that's still reasonable in price (unlike Sport Cups). There's a reason why many people run these tires at national level events.

Your pressures are WAY too high. You need to be in the mid 30s if you want grip. Given that these tires have stiff sidewall, you don't need to run as high of pressure.


Tires definitely heat up (although not as much as a track session) and it's a little more than 3-4 psi if you're pushing the car enough and the tires are sticky. The interval between your runs varies by club, but you actually need to be constantly checking/adjusting your pressure before/after each run until about your 4th run or so.

Get some chalk and mark your tires from the edge of shoulder tread block to the sidewall, so you can see how much rollover you're getting (will vary based on tires, camber, psi, etc). Then find the tread marker on the sidewall of the tire to see where the rollover needs to stop ideally. From there, you just adjust tire pressure and camber as appropriate. Having a pyrometer helps but I wouldn't worry about that now. Of course, if you don't have enough seat time, none of this should be your primary concern, but that's another point.

BTW, for FWD, you want more pressure in the rear so you can get the rear to rotate easier. By adding pressure (and that much at that) to the front, all you're doing is introducing more understeer.

No offense, but I think you need to start making friends at your local autocross who is national level or very competitive locally, because I get the feeling you're doing things without proper guidance or someone's feeding you bad advice.

What clubs are you racing with in Chicago?
Thanks for the advice.
I do all the stuff you mentioned above. (checking pressure, marking with chalk...etc)

I ran with CCSCC in rantoul, IL little over 2 yrs.
I did about 20+ autocross event 7~8 years ago but I was not that competitive driver anyway.
I did Autocross class they offered and I did learn a lot of what you explained.
They do have several good drivers.


For my current car, it's got MPSS. That side wall is soft.
I started at 40 psi but it rolled down to sidewall. lol
So I had to keep pumping up. It was stable around 45~46 after 3 runs. (peaked at 48)
Rear was good at 35 psi.

Maybe I will start with 35~38 psi next time see how far I wear down on the sidewall.

Once I get RE71 later, I will try lower pressure.
I saw couple of E90 M3 running 33 psi in front with RE71. So It will be good starting point.
Appreciate 0
      04-25-2018, 11:16 AM   #82
cxp213
Lieutenant
cxp213's Avatar
277
Rep
554
Posts

Drives: M235i
Join Date: Apr 2017
Location: TX

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
Thanks for the advice.
I do all the stuff you mentioned above. (checking pressure, marking with chalk...etc)

I ran with CCSCC in rantoul, IL little over 2 yrs.
I did about 20+ autocross event 7~8 years ago but I was not that competitive driver anyway.
I did Autocross class they offered and I did learn a lot of what you explained.
They do have several good drivers.


For my current car, it's got MPSS. That side wall is soft.
I started at 40 psi but it rolled down to sidewall. lol
So I had to keep pumping up. It was stable around 45~46 after 3 runs. (peaked at 48)
Rear was good at 35 psi.

Maybe I will start with 35~38 psi next time see how far I wear down on the sidewall.

Once I get RE71 later, I will try lower pressure.
I saw couple of E90 M3 running 33 psi in front with RE71. So It will be good starting point.
Chicago Region SCCA and Milwaukee Region SCCA has some fast guys, so you might want to check them out. If you like a more relaxed club, Windy City Miata guys are one of the chillest; at least they were when I used to go to their events.

For AX, I keep my tires (not just 71Rs and Rivals, but also the previous "it" tires before that like RS3s, SS ZIIs, etc) around 32-33psi hot (slightly lower in the back to help with corner exits).

The fastest way to get better at AX is not to just attend more AX events, but to attend the test and tune days for those who campaign on a regular basis. Those guys will usually rent out a lot for themselves to set up figure 8s, slaloms, etc so they can fine tune their suspension and dial in their alignment on the spot for that particular surface. You'll get way more runs and get much better advice at these types of "events" as long as you're committed to testing various set ups on your car.
Appreciate 0
      04-25-2018, 11:36 AM   #83
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by cxp213 View Post
Chicago Region SCCA and Milwaukee Region SCCA has some fast guys, so you might want to check them out. If you like a more relaxed club, Windy City Miata guys are one of the chillest; at least they were when I used to go to their events.

For AX, I keep my tires (not just 71Rs and Rivals, but also the previous "it" tires before that like RS3s, SS ZIIs, etc) around 32-33psi hot (slightly lower in the back to help with corner exits).

The fastest way to get better at AX is not to just attend more AX events, but to attend the test and tune days for those who campaign on a regular basis. Those guys will usually rent out a lot for themselves to set up figure 8s, slaloms, etc so they can fine tune their suspension and dial in their alignment on the spot for that particular surface. You'll get way more runs and get much better advice at these types of "events" as long as you're committed to testing various set ups on your car.
Those guys often comes to CCSCC auto x and they typically wins FTDI.

http://ccsportscarclub.org/

When I had MkV GTI, I had Kumho XS and typically ran 42~43 psi in front if I don't want to wore down to tire name. lol
I understand your point of running mid 30 psi as much as popssible but if tire rolls down below thread block (down to erase tire spec labels lol), I couldn't go any lower.
Again, it's most likely the driver.

Also, I am running 100 % stock and no plan to adjust any setup.
(no camber adjustment in front anyway)
If I am that serous about it, I wouldn't buy M240. I would get Focus st or GTI for GS.

Still, I do enjoy auto x and definitely keep doing it.
Appreciate 0
      04-25-2018, 11:48 AM   #84
cxp213
Lieutenant
cxp213's Avatar
277
Rep
554
Posts

Drives: M235i
Join Date: Apr 2017
Location: TX

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
Those guys often comes to CCSCC auto x and they typically wins FTDI.

http://ccsportscarclub.org/

When I had MkV GTI, I had Kumho XS and typically ran 42~43 psi in front if I don't want to wore down to tire name. lol
I understand your point of running mid 30 psi as much as popssible but if tire rolls down below thread block (down to erase tire spec labels lol), I couldn't go any lower.
Again, it's most likely the driver.

Also, I am running 100 % stock and no plan to adjust any setup.
(no camber adjustment in front anyway)
If I am that serous about it, I wouldn't buy M240. I would get Focus st or GTI for GS.

Still, I do enjoy auto x and definitely keep doing it.
Nothing like taking FTD (index or not)!

Yeah, back in the day, adding pressure was fine but the newer crops of tires don't do as well with those kinds of pressures.

I guess it also helps to know that you're completely stock and plan on staying that way, since that would change the type of advice given, lol.

Good call on the GS class, lol -- their PAX is soft. FS is a bit soft, too, but the 2-series is not competitive in that class. With regards to the level of competition and fun with modding a car, the ST classes are where it's at, imo.
Appreciate 1
TajoMan59.00

      04-25-2018, 11:53 AM   #85
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by cxp213 View Post
Nothing like taking FTD (index or not)!

Yeah, back in the day, adding pressure was fine but the newer crops of tires don't do as well with those kinds of pressures.

I guess it also helps to know that you're completely stock and plan on staying that way, since that would change the type of advice given, lol.

Good call on the GS class, lol -- their PAX is soft. FS is a bit soft, too, but the 2-series is not competitive in that class. With regards to the level of competition and fun with modding a car, the ST classes are where it's at, imo.
I did not know about the newer tires don't do well at higher pressure.
Good to know. I will keep in mind.

Maybe I should try 35 psi with MPSS and see how bad it rolls.
Appreciate 0
      04-25-2018, 11:56 AM   #86
cxp213
Lieutenant
cxp213's Avatar
277
Rep
554
Posts

Drives: M235i
Join Date: Apr 2017
Location: TX

iTrader: (0)

Quote:
Originally Posted by TajoMan View Post
I did not know about the newer tires don't do well at higher pressure.
Good to know. I will keep in mind.

Maybe I should try 35 psi with MPSS and see how bad it rolls.
Part of your issue is that you don't have enough negative camber, so you'll have rollover regardless. You could also be overdriving, so maybe take it easier than you normally would on your first run and incrementally ramp up your aggressiveness. When I instruct, I tell them to take it at around 70% on their first run because beginners still overshoot anyway (not that you're a novice). At any rate, the most important thing is that you're getting out there and having fun so as long as that's happening, the rest is just icing on the cake.
Appreciate 1
      04-25-2018, 02:39 PM   #87
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

Quote:
Originally Posted by cxp213 View Post
Part of your issue is that you don't have enough negative camber, so you'll have rollover regardless. You could also be overdriving, so maybe take it easier than you normally would on your first run and incrementally ramp up your aggressiveness. When I instruct, I tell them to take it at around 70% on their first run because beginners still overshoot anyway (not that you're a novice). At any rate, the most important thing is that you're getting out there and having fun so as long as that's happening, the rest is just icing on the cake.
yep. Having fun is the most important part.
Appreciate 1
cxp213276.50

      07-09-2018, 03:50 PM   #88
TajoMan
Second Lieutenant
59
Rep
220
Posts

Drives: 17 M240 xdrive
Join Date: Mar 2017
Location: Chicago, IL

iTrader: (0)

I did another Auto X couple of weeks ago.

Tried to stay as low as possible on front pressure (40~42 psi).
Little triangle for wear mark is now gone. lol

MPSS does not like hot weather at all. It does get greasy and sidewall gets even softer.

I would say I have to pump up 45 psi hot to keep it rolling down too much.

Can wait to wear down these tires and get RE71r.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -5. The time now is 07:15 AM.




2addicts
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST