Pandora Car Alarm System
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   BMW M3 and BMW M4 Forum > BMW F80 M3 / F82 M4 Technical Topics > Wheels | Tires -- Sponsored by The Tire Rack

Post Reply
 
Thread Tools Search this Thread
      01-14-2014, 08:42 PM   #1
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Question New 275/35 19 Michelin PSS for the F8X?

When I decided to switch to 275/35R19 tires on my E92, I did some in depth research to understand the differences between a 265/35 and a 275/35 regarding contact patch dimensions and tire weight tradeoff. I came to the conclusion that the 275 offered 20% more rubber on the road vs the 265 mostly due to smaller grooves in the thread.

http://www.m3post.com/forums/showthread.php?t=848092

Based on the picture from the Detroit release, it seems that the 275/35 on the F8X has the wider grooves of the 265 tire (also as on the 235/35, 245/35 and 255/35). See picture below of the 275/35 on my E92 vs the 275/35 on the F80.
Attached Images
  

Last edited by CanAutM3; 02-13-2015 at 08:15 AM..
Appreciate 0
      01-14-2014, 08:49 PM   #2
solstice
Major General
5457
Rep
7,037
Posts

Drives: 2015 M3 6MT
Join Date: May 2013
Location: Seattle

iTrader: (0)

Try measuring each groove and contact stripe, add the combined of each and calculate the ratio of groove vs patch.
Appreciate 0
      01-14-2014, 08:52 PM   #3
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by solstice View Post
Try measuring each groove and contact stripe, add the combined of each and calculate the ratio of groove vs patch.
Have a look at the thread I reference to in my OP.
Appreciate 0
      01-14-2014, 09:01 PM   #4
LDSM
Captain
LDSM's Avatar
United_States
343
Rep
686
Posts

Drives: ...
Join Date: Jun 2012
Location: ...

iTrader: (0)

Reading the sidewalls the tires on the show cars are 255/35 19
Appreciate 0
      01-14-2014, 09:03 PM   #5
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by elevenfive View Post
Reading the sidewalls the tires on the show cars are 255/35 19
255/35 in front, but 275/35 in the rear. The picture I posted is from the rear tires.
Appreciate 0
      01-14-2014, 09:06 PM   #6
Jockey
Brigadier General
Jockey's Avatar
3439
Rep
4,981
Posts

Drives: 992 C4S
Join Date: Mar 2008
Location: Park City, UT

iTrader: (1)

I think it may be part of an optical illusion between a tire with full tread and a tire near it's wear bars
Appreciate 0
      01-14-2014, 09:07 PM   #7
LDSM
Captain
LDSM's Avatar
United_States
343
Rep
686
Posts

Drives: ...
Join Date: Jun 2012
Location: ...

iTrader: (0)

Quote:
Originally Posted by CanAutM3 View Post
255/35 in front, but 275/35 in the rear. The picture I posted is from the rear tires.

Ah my mistake, I was looking at the fronts
Appreciate 0
      01-14-2014, 09:12 PM   #8
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by Jockey View Post
I think it may be part of an optical illusion between a tire with full tread and a tire near it's wear bars
I don't believe it is. When I got my new 275, the sea/land ratio looked very much like the picture of my worn set and not like the ones on the F80.
Appreciate 0
      01-14-2014, 09:14 PM   #9
Jockey
Brigadier General
Jockey's Avatar
3439
Rep
4,981
Posts

Drives: 992 C4S
Join Date: Mar 2008
Location: Park City, UT

iTrader: (1)

I'm sure tirerack could answer your question then.

Trying to judge this from differing distances with different wear patterns is only going to lead to guesses.
Appreciate 0
      01-14-2014, 09:23 PM   #10
Needsdecaf
Major General
Needsdecaf's Avatar
6363
Rep
6,571
Posts

Drives: 2024 G80 Comp xDrive
Join Date: Feb 2011
Location: The Woodlands, TX

iTrader: (0)

That's ok, we need it down here in TX to deal with all the water!
Appreciate 0
      01-14-2014, 09:48 PM   #11
solstice
Major General
5457
Rep
7,037
Posts

Drives: 2015 M3 6MT
Join Date: May 2013
Location: Seattle

iTrader: (0)

Quote:
Originally Posted by Needsdecaf View Post
That's ok, we need it down here in TX to deal with all the water!
Same here, I got the 265s and they are awesome in the wet which we have enough of here in Seattle...
I'm actually putting on a new set of rears on this Friday after 24k miles on the first set. Superb tires.
Appreciate 0
      01-14-2014, 09:54 PM   #12
GregW / Oregon
Commander-In-Chief
2070
Rep
8,898
Posts

Drives: 2023 M2 Coupe, 2020 GLE 450
Join Date: Nov 2005
Location: Lake Oswego, OR

iTrader: (3)

Garage List
Contact patch

Quote:
Originally Posted by CanAutM3 View Post
When I decided to switch to 275/35R19 tires on my E92, I did some in depth research to understand the differences between a 265/35 and a 275/35 regarding contact patch dimensions and tire weight tradeoff. I came to the conclusion that the 275 offered 20% more contact path width vs the 265 mostly due to smaller grooves in the thread.
Regardless of contact patch width, the area will be the same.
__________________

Greg Lake Oswego, Oregon, USA
2023 M2 Coupe - Brooklyn Grey/Cognac/CF, 6MT; 2020 MB GLE 450
Appreciate 0
      01-15-2014, 08:44 AM   #13
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by GregW / Oregon View Post
Regardless of contact patch width, the area will be the same.
I see where you are coming from and agree. I have debated this myslef manytimes: for a given inflation pressure, increasing the width of a tire changes the contact patch shape but does not linearly change the contact patch size.

However here we are not discussing contact patch size. The contact patch is the the area where the tire deforms to contact the road. The pressure inside the tire times the contact patch area equals the load the tire is carrying (minus the load the sidewall is carrying). This area remains relatively constant regardless of the thread pattern of the tire; this because the air pushes on the inside of the tire and not on the individual thread blocks. So a slick tire will have the same contact patch size (tire deformation) than a wet tire with big grooves (assuming same inflation pressure and sidewall stiffness). However, since the slick tire does not have any grooves, it has much more rubber in contact with the road and therefore more grip.

Comparing the two 275/35 PSS tires above, both will have essentially the same contact patch area, but the one with the smaller grooves will have more rubber in contact with the road, hence more grip.

Last edited by CanAutM3; 12-28-2015 at 10:12 AM..
Appreciate 0
      01-15-2014, 01:42 PM   #14
bavarian19
General
bavarian19's Avatar
United_States
516
Rep
18,858
Posts

Drives: Car
Join Date: Mar 2005
Location: VA

iTrader: (23)

More rubber in contact with the road does not mean more grip. It means the total distribution of weight is over a larger surface area, so less downward pressure per square inch.

Measuring grip is much more complex than that.
Appreciate 0
      01-15-2014, 02:42 PM   #15
CanAutM3
General
CanAutM3's Avatar
Canada
21105
Rep
20,741
Posts

Drives: 2021 911 turbo
Join Date: Jan 2012
Location: Montreal

iTrader: (1)

Garage List
Quote:
Originally Posted by bavarian19 View Post
More rubber in contact with the road does not mean more grip. It means the total distribution of weight is over a larger surface area, so less downward pressure per square inch.

Measuring grip is much more complex than that.
Yes, I know, the physics of tire grip are very complex. But more rubber in contact with the road does mean more grip.

A tire gripping the road is more than just normal force times the friction coefficient as you imply. There are two major components to tire grip: standard friction and rubber element interlocking with the pavement irregularities. The later is directly related to how much rubber is contact with the road. Otherwise, why would race cars use slicks?

Last edited by CanAutM3; 01-15-2014 at 03:48 PM..
Appreciate 0
      01-15-2014, 03:59 PM   #16
aajami
Brigadier General
aajami's Avatar
United_States
430
Rep
4,567
Posts

Drives: Space Gray '09 E92 M3
Join Date: Dec 2008
Location: Manhattan Beach, CA

iTrader: (4)

This is the part where I hijack the thread and complain that Michelin has yet to develop a 285/30-19 application of the PSS.
__________________
'09 E92 M3: Space Gray, Black, Carbon Leather | ZTP 2MK ZPP 2MT 6FL | link 1 / link 2
Mods: M Performance exhaust | ZCP retrofit | Euro airbox | GTS DCT flash | JPN 240 ECU flash | Euro LCI taillights | CRT lip | OEM alarm retrofit | Space Gray bumper plugs | BMW Performance: Mk. II spoiler / Mk. II non-electronic steering wheel / mirror caps / front grilles / side gills / intake louvers / emblem
Appreciate 0
      01-16-2014, 02:09 AM   #17
swamp2
Lieutenant General
swamp2's Avatar
United_States
609
Rep
10,407
Posts

Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

iTrader: (3)

Let's not forget correcting the very common misconception that a wider tire has the same contact area as a narrower tire at the same inflation pressure. This is certainly a bit OT to the OP but was being discussed. This "fact" works for things like spherical balloons, not tires with heavy steel belts, stiff side walls and stiff solid rubber tread blocks.

This myth is very clearly refuted here.
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
| Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors |
| Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels |
| XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit |
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 09:09 AM.




f80post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
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