BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Wheels + Tires Sponsored by The Tire Rack
  TireRack

KEEP M3POST ALIVE BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER LINK!
Post Reply
 
Thread Tools Search this Thread
      11-26-2014, 07:36 AM   #1
LarThaL
Colonel
LarThaL's Avatar
65
Rep
2,637
Posts

 
Drives: 2011 M3
Join Date: Apr 2011
Location: West Springfield, MA

iTrader: (0)

Question on increased stagger and understeer

If you increase the stagger from the stock 245/265 to a 255/295 set-up is the increase in understeer really noticeable, or not really?

Is the added grip worth the trade-off? I don't want to go wider than 255 in front because I want to maintain steering feel, but also want to maximize rear grip without increasing understeer during more aggressive driving. Is a 255/275 set-up the best way to go?
__________________
Precision tool: 2011 BMW ///M3
Sledgehammer: 2014 Audi S6

Appreciate 0
      11-26-2014, 07:54 AM   #2
s85e90
Colonel
30
Rep
2,445
Posts

 
Drives: black e90
Join Date: Jan 2014
Location: everywhere

iTrader: (0)

You can have an alignment to dial back out the understeer. I run 245 fronts and 285 rears.
Appreciate 0
      11-26-2014, 02:41 PM   #3
Hujan
Lieutenant Colonel
United_States
27
Rep
1,972
Posts

 
Drives: 2013 E92 M3; 2010 Z4 35i
Join Date: Apr 2013
Location: San Diego, CA

iTrader: (4)

Good question. I would like to know others' experiences as well.

I assume that understeer/oversteer is a function of grip. The wisdom being that if you reduce front-end grip and increase rear-end grip on the E92 M3, you will increase understeer. Assuming that's the case, I found it interesting that Michelin PSS in 255/35/19 on 9" wheels actually have a bigger contact patch (narrower but much longer) than Michelin PSS in 275/30/19 on 9.5" wheels. (Michelin PSS in 295/30/19 on 10.5" wheels have a larger contact patch than 275/35/19 on 10" wheels, though.)

Thus, if that data is accurate, it would seem that the overall grippiest setup (at least on Michelin PSS) would be 255/35/19 on 19 x 9" wheels up front, and 295/30/19 on 10.5" wheels in the rear.

http://bndtechsource.ucoz.com/index/...alculator/0-20
__________________
E92 M3: BPM Sport Stg. 2 | Akrapovic Evolution | Brembo GT 380/380 | Ohlins R&T w/ Vorshlags | RD Sport sways

E89 Z4 35i: Cobb Stg. 1+ | Evolution Racewerks FMIC w/ CP | Tial BOV | BMS filter | BMS OCC | BMS oil thermo
Appreciate 0
      11-26-2014, 02:43 PM   #4
1MOREMOD
2014 Track Days - 11|Ridge 1:52:24|Pacific 1:35:72
1MOREMOD's Avatar
United_States
174
Rep
13,015
Posts

 
Drives: Race car->
Join Date: Mar 2009
Location: check your mirrors

iTrader: (5)

Quote:
Originally Posted by s85e90 View Post
You can have an alignment to dial back out the understeer. I run 245 fronts and 285 rears.
This. If it's for street doesn't matter much anyways.
Appreciate 0
      11-26-2014, 05:17 PM   #5
Flying Ace
Captain
Flying Ace's Avatar
31
Rep
953
Posts

 
Drives: Sopwith M-Camel, E90 M3
Join Date: Jul 2014
Location: San Francisco, CA

iTrader: (3)

255/295 what tires will you be buying?
Appreciate 0
      11-26-2014, 05:29 PM   #6
1MOREMOD
2014 Track Days - 11|Ridge 1:52:24|Pacific 1:35:72
1MOREMOD's Avatar
United_States
174
Rep
13,015
Posts

 
Drives: Race car->
Join Date: Mar 2009
Location: check your mirrors

iTrader: (5)

I drink old E to increase my stagger.
Appreciate 0
      11-27-2014, 09:06 AM   #7
LarThaL
Colonel
LarThaL's Avatar
65
Rep
2,637
Posts

 
Drives: 2011 M3
Join Date: Apr 2011
Location: West Springfield, MA

iTrader: (0)

Quote:
Originally Posted by 1MOREMOD View Post
This. If it's for street doesn't matter much anyways.
Actually I am gearing up to spend more time at the track. A really nice new track is being built 20 minutes from where I live. I will be buying a club membership.

Yes, yes.....I know about understeer, stagger, etc, but that is why I am wondering if this amount of increased stagger and increased understeer is more theory or is it a real phenomenon. The GTS M3 uses a 255/285 set up so 30mm obviously works just fine. I don't care about the fastest times, etc. I am not racing for money. It is all about fun and the subjective driving experience.

I am looking for the best possible combination of feel, responsiveness and grip at track speeds, as opposed to street speeds. Again...I am not looking for the set-up that will necessarily give me the fastest time, just the best subjective track experience. My top choice right now is actually to go with a 265/35/18 and 285/35/18 set-up on Apex wheels.

Here is the track at Palmer Motorsports Park in Palmer, MA. Scheduled to open spring/summer of 2015:

https://www.youtube.com/watch?v=A7VmLvAVBrI
__________________
Precision tool: 2011 BMW ///M3
Sledgehammer: 2014 Audi S6


Last edited by LarThaL; 11-27-2014 at 09:17 AM.
Appreciate 0
      11-27-2014, 09:18 AM   #8
surlynkid
Major
surlynkid's Avatar
10
Rep
1,055
Posts

 
Drives: 2013 E92 M3
Join Date: Apr 2012
Location: League City, TX

iTrader: (1)

Garage List
i run 265/30 and 295/30 on the street. But that is the street. I am not doing anything ridiculous enough on the street for understeer to matter. 275/35-18 at the track.
__________________
Stoptech 380mm/355mm | Pagid RS-29 | Akrapovic EVO - CF tips | Benvo Tune | MS UDP | AA air filter | Apex EC-7 18x10 square 275/35-18 NT01 | Turner Race Studs | GT4 Brake Cooling | GT4 Power Steering Cooling | Performance Steering Wheel | CF Mirror Caps | CF Spoiler | Varis System 1 Full CF Diffuser | Extended Paddle Shifters | Schroth Quick Fit Pro | Turner Steering Rack Stops | Vorshlag Camber Plates | AiM Solo DL
Appreciate 0
      11-27-2014, 10:13 AM   #9
1MOREMOD
2014 Track Days - 11|Ridge 1:52:24|Pacific 1:35:72
1MOREMOD's Avatar
United_States
174
Rep
13,015
Posts

 
Drives: Race car->
Join Date: Mar 2009
Location: check your mirrors

iTrader: (5)

I've always used square set up at the track. Car from factory has less grip up front and want to reduce that tendency. Adding front camber and width of front tire is how most achieve that more neutral balance.
Appreciate 0
      11-27-2014, 12:09 PM   #10
Hujan
Lieutenant Colonel
United_States
27
Rep
1,972
Posts

 
Drives: 2013 E92 M3; 2010 Z4 35i
Join Date: Apr 2013
Location: San Diego, CA

iTrader: (4)

I am running 275/35-18 front and 295/35-28 rear G Force Rivals on Apex EC-7 on my track wheels. No track time with them yet, but just from playing with them on the street I'm pretty excited about their track potential.
__________________
E92 M3: BPM Sport Stg. 2 | Akrapovic Evolution | Brembo GT 380/380 | Ohlins R&T w/ Vorshlags | RD Sport sways

E89 Z4 35i: Cobb Stg. 1+ | Evolution Racewerks FMIC w/ CP | Tial BOV | BMS filter | BMS OCC | BMS oil thermo
Appreciate 0
      11-29-2014, 08:38 AM   #11
bigjae1976
That's what she said...
bigjae1976's Avatar
84
Rep
5,651
Posts

 
Drives: 11 E90 M3 Individual
Join Date: Mar 2006
Location: Milwaukee, WI

iTrader: (12)

Garage List
2004 BMW M3  [4.50]
2011 BMW E90 M3  [5.00]
2013 BMW 328i  [5.00]
The only reason I run a square sized tire setup is so that I can rotate tires. What a PIA if you cord a front tire and you only have an extra rear tire.

Run a staggered set up. Stuff as much back there as you can (that's what she said). In an ideal world, I'd run 275/295.
__________________


Sponsored by Momentum BMW #593...We Bleed BMW BLUE!
Appreciate 0
      11-29-2014, 08:43 PM   #12
Richbot
Colonel
30
Rep
2,130
Posts

 
Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

iTrader: (2)

Don't just look at width when considering stagger. A 245/40-18 front and 285/40-18 rear, for instance, would yield a car with more steady-state cornering Understeer but more wheelspin on corner exit due to shorter tire with shorter sidewall and gearing, all else being equal. I haven't tried it yet but I think this car's happy place (because you can only run so much front tire) may be a 275 front and rear setup, with a taller rear aspect ratio

My theory is that What the car, which is somewhat pushy-loose from the factory, needs is better corner entry to apex grip (bigger front tire) and more throttle-on grip (taller rear tire) to balance that extra front grip once you start feeding in throttle. A 275/295 setup gets you part way there that's what I'm running now, but still feel now that I have all this front grip the rear starts to run out of stick when I ask it to power out of corners mostly due to overpowering the outside rear when feeding in throttle.
__________________
Appreciate 0
      11-29-2014, 09:45 PM   #13
bigjae1976
That's what she said...
bigjae1976's Avatar
84
Rep
5,651
Posts

 
Drives: 11 E90 M3 Individual
Join Date: Mar 2006
Location: Milwaukee, WI

iTrader: (12)

Garage List
2004 BMW M3  [4.50]
2011 BMW E90 M3  [5.00]
2013 BMW 328i  [5.00]
Quote:
Originally Posted by Richbot View Post
Don't just look at width when considering stagger. A 245/40-18 front and 285/40-18 rear, for instance, would yield a car with more steady-state cornering Understeer but more wheelspin on corner exit due to shorter tire with shorter sidewall and gearing, all else being equal. I haven't tried it yet but I think this car's happy place (because you can only run so much front tire) may be a 275 front and rear setup, with a taller rear aspect ratio

My theory is that What the car, which is somewhat pushy-loose from the factory, needs is better corner entry to apex grip (bigger front tire) and more throttle-on grip (taller rear tire) to balance that extra front grip once you start feeding in throttle. A 275/295 setup gets you part way there that's what I'm running now, but still feel now that I have all this front grip the rear starts to run out of stick when I ask it to power out of corners mostly due to overpowering the outside rear when feeding in throttle.
I think the biggest problem with the OE suspension is the lack of travel. I've got a Dinan stage 2 and had GC plates. I know I'm on the bump stops whenever you add a considerable amount of power and more rear spring would certainly help.

I never thought of running a taller tire in the rear to help that. Interesting. I'd try and fit a 305 but now you are talking about some serious tire money. Screw that....I'll just drift my way around thank you very much!
__________________


Sponsored by Momentum BMW #593...We Bleed BMW BLUE!
Appreciate 0
      11-30-2014, 12:17 AM   #14
FogCityM3
Lieutenant Colonel
FogCityM3's Avatar
36
Rep
1,744
Posts

 
Drives: M3 (E90)
Join Date: Feb 2012
Location: San Francisco

iTrader: (0)

Believe the M3 GTS also runs spacers at the front and rear (with wider front spacers). This will have the effect of dialing out some understeer, so you have to look at the combination of track (offset) in addition to tire sizes.

Quote:
Originally Posted by LarThaL View Post
Actually I am gearing up to spend more time at the track. A really nice new track is being built 20 minutes from where I live. I will be buying a club membership.

Yes, yes.....I know about understeer, stagger, etc, but that is why I am wondering if this amount of increased stagger and increased understeer is more theory or is it a real phenomenon. The GTS M3 uses a 255/285 set up so 30mm obviously works just fine. I don't care about the fastest times, etc. I am not racing for money. It is all about fun and the subjective driving experience.

I am looking for the best possible combination of feel, responsiveness and grip at track speeds, as opposed to street speeds. Again...I am not looking for the set-up that will necessarily give me the fastest time, just the best subjective track experience. My top choice right now is actually to go with a 265/35/18 and 285/35/18 set-up on Apex wheels.

Here is the track at Palmer Motorsports Park in Palmer, MA. Scheduled to open spring/summer of 2015:

https://www.youtube.com/watch?v=A7VmLvAVBrI
__________________
BPM Stage I Dev Tune | MPE Cat-Back Exhaust | ATS Superlight 19" Wheels | Essex/AP-Racing Lightweight BBK | Cantrell Motorsports Brake Ducts | Dinan Pulley | Dinan CF Strut Braces | Dinan CF Elbow | Göke Carbontechnik CF Plenum | Technocraft Envy Intake | BMW M Perf E Steering Wheel | BMW CF Splitters/Spoiler/Mirror Caps | M Perf Pedals | M5 Shift Knob | BMW OEM Grills/Gills/Hood Vents
Appreciate 0
      11-30-2014, 09:20 AM   #15
Richbot
Colonel
30
Rep
2,130
Posts

 
Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

iTrader: (2)

I agree this car corners on the bumpstops in stock form frequently but I also don't think the bumpstops on this car are all that harsh a transition. Travel when you start compressing the bumpstops is still travel and the stops on this car are long and very progressive otherwise with the very soft stock spring rates (considering how heavy it is and how much grip it generates, about 1g on modern tires like the PSS) the car would ride like an anvil and be useless over bumps even when stock, and we know that's not true.

So if you're interested in staying with near stock spring rates you're going to be on the stops anyway and might as well find other ways to get the balance right

I also agree sideways are the best ways
__________________
Appreciate 0
      11-30-2014, 07:28 PM   #16
bigjae1976
That's what she said...
bigjae1976's Avatar
84
Rep
5,651
Posts

 
Drives: 11 E90 M3 Individual
Join Date: Mar 2006
Location: Milwaukee, WI

iTrader: (12)

Garage List
2004 BMW M3  [4.50]
2011 BMW E90 M3  [5.00]
2013 BMW 328i  [5.00]
Quote:
Originally Posted by Richbot View Post
I also agree sideways are the best ways
__________________


Sponsored by Momentum BMW #593...We Bleed BMW BLUE!
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
Forum Jump


All times are GMT -5. The time now is 04:47 AM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, 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