M5POST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read

Go Back   M5POST - BMW M5 Forum > F10 M5 Forum > Wheels | Tires | Suspension | Brakes | Chassis

Post Reply
 
Thread Tools Search this Thread
      06-11-2012, 06:15 AM   #1
Trips
Private First Class
 
Trips's Avatar
 
Drives: '13 m5, '10 r8 v10
Join Date: Jan 2009
Location: NW Indiana

Posts: 133
iTrader: (0)

Big difference between 19" and 20" wheels for winter duty?

I prefer the looks of the 20" oem wheels but have heard the 19" wheels do much better in the snow. Thoughts on this guys?

Thx!
Trips is offline  
0
Reply With Quote
      06-11-2012, 08:47 AM   #2
SleepTight
Second Lieutenant
 
SleepTight's Avatar
 
Drives: 2013 BMW M5
Join Date: Dec 2009
Location: Long Island, New York

Posts: 286
iTrader: (0)

It is simple physics. The wider the tire, the wider the path it has to "plow" through deep snow and the greater chance of losing traction--particularly at the rear wheels in the M5. I would recommend the standard M5 19" wheels for winter duty not because of their smaller diameter, but because of their narrower widths of 265/40 R19 front and 295/35 R19 rear.

The optional M5 20" wheels are 265/35 R20 front 295/30 R20 rear.

It is possible that some other 19" wheel with an even narrower width will also fit the M5, which (assuming that it didn't radically upset the M5's delicate suspension) would be an even better choice for driving in snow, but we know for sure that the standard 19"s will fit so that's probably the way to go for now.
SleepTight is offline   United_States
0
Reply With Quote
      06-11-2012, 10:49 AM   #3
PatrickC23
Lieutenant Colonel
 
PatrickC23's Avatar
 
Drives: '13 F10 AW/SO ///M5
Join Date: Apr 2012
Location: NNJ

Posts: 1,605
iTrader: (0)

Garage List
2013 BMW ///M5  [0.00]
Quote:
Originally Posted by SleepTight View Post
It is simple physics. The wider the tire, the wider the path it has to "plow" through deep snow and the greater chance of losing traction--particularly at the rear wheels in the M5. I would recommend the standard M5 19" wheels for winter duty not because of their smaller diameter, but because of their narrower widths of 265/40 R19 front and 295/35 R19 rear.

The optional M5 20" wheels are 265/35 R20 front 295/30 R20 rear.

It is possible that some other 19" wheel with an even narrower width will also fit the M5, which (assuming that it didn't radically upset the M5's delicate suspension) would be an even better choice for driving in snow, but we know for sure that the standard 19"s will fit so that's probably the way to go for now.
Im assuming OP is referring to the wheel size with a winter snow tire in mind as well. If so then the width of the stock tires would not matter. However, Im assuming the 19" wheel is more narrow than the 20" wheel, which would allow for a skinnier snow tire, which was your argument.

Also, I'm assuming with a tire that has a larger sidewall by an inch would provide a deeper tread, aiding in snow traction. In that case I'd say 19's are better.
__________________
Retired - 2009 C63 l 2007 Supercharged RRS l 2002 e46 SMG ///M3 l 2001 e46 330ci

2013 Alpine White/Sakhir Orange F10 M5 - 20" Modulare Matte Titanium Brushed B18s - Coded by the best, V12
2014 Jeep JKU Wrangler Willys Wheeler W Unlimited - Granite Crystal/Black
PatrickC23 is online now   United_States
0
Reply With Quote
      06-11-2012, 11:10 AM   #4
ucla95
Striker
 
Drives: M9
Join Date: May 2012
Location: Plains

Posts: 464
iTrader: (0)

Is it true that the 19's are narrower than the 20's?
ucla95 is offline  
0
Reply With Quote
      06-11-2012, 11:43 AM   #5
nybimmerfan
First Lieutenant
 
nybimmerfan's Avatar
 
Drives: 2013 MCB M5
Join Date: May 2012
Location: NY

Posts: 396
iTrader: (0)

I thought that the width would be the same and only the sidewall is different as both have widths of 265 (in mm) for the front and 295 for the rear. If expressed in inches 265/25.4 would be 10.43 inches wide front and 295/25.4 would be 11.61 inches wide rear. Now it is the sidewall aspect ratio that are different. So where is the width difference being discussed?
nybimmerfan is offline   United_States
0
Reply With Quote
      06-11-2012, 11:54 AM   #6
stealth.pilot
Brigadier General
 
stealth.pilot's Avatar
 
Drives: 2014 M5 Individual
Join Date: Aug 2010
Location: South East USA

Posts: 4,310
iTrader: (0)

Width and tread depth are the same.

The only difference is that the 19" tire is more flexible, and so will maintain contact better.
__________________
2014 ///M5 Individual Frozen Grey, Silverstone Full Merino, Piano Black, Exec Pkg, Drivers assistance plus, LED Pkg, Bang and Olufsen, 20" 343M Forged Alloy Wheels
Countermeasures: Bel StiR+, Laser Interceptor Quad HP, Zaon MRX
Upgrades: Eisenmann Sport with M Performance tips, Dinan anti-roll bars
stealth.pilot is offline   United Kingdom
0
Reply With Quote
      06-11-2012, 12:04 PM   #7
PatrickC23
Lieutenant Colonel
 
PatrickC23's Avatar
 
Drives: '13 F10 AW/SO ///M5
Join Date: Apr 2012
Location: NNJ

Posts: 1,605
iTrader: (0)

Garage List
2013 BMW ///M5  [0.00]
I was mistaken, 20x10 rear and 19x10 rear, so it's the same.
__________________
Retired - 2009 C63 l 2007 Supercharged RRS l 2002 e46 SMG ///M3 l 2001 e46 330ci

2013 Alpine White/Sakhir Orange F10 M5 - 20" Modulare Matte Titanium Brushed B18s - Coded by the best, V12
2014 Jeep JKU Wrangler Willys Wheeler W Unlimited - Granite Crystal/Black
PatrickC23 is online now   United_States
0
Reply With Quote
      06-11-2012, 01:11 PM   #8
Trips
Private First Class
 
Trips's Avatar
 
Drives: '13 m5, '10 r8 v10
Join Date: Jan 2009
Location: NW Indiana

Posts: 133
iTrader: (0)

Same width front and back for both sizes, 9 front and 10 back. I'd be putting the same size tires all the way around for either size, 255s I believe.

I think the only difference then would be an extra 1/2" of sidewall height on the 19s. I know this improves ride comfort as well as handling, but is it a big deal for performance in the snow, safety wise?

Thanks again.
Trips is offline  
0
Reply With Quote
      06-11-2012, 04:50 PM   #9
mdh
Private First Class
 
Drives: E60 M5
Join Date: Apr 2008
Location: Midwest

Posts: 139
iTrader: (0)

I ran the Pirelli's in the OEM size (19" wheels 255/40f, 285/35r) on my E60 M5. I could not even back out of our driveway without spinning the tires in the snow. With 400+ lbs of weight in the trunk, the snow performance was tolerable. If you want to have reasonable traction in the snow, FOLLOW THE BMW RECOMENDATIONS! The recommendation was to run '4-square' 255/40-19's all around as the previous poster did. I didn't, because I really hated the way the Blizzaks felt in the dry, and then I switched to more performance oriented snow tires, and still didn't like the dry handling. I went with the OEM setup because I got much better handling in the dry. I would not do this if you want any kind of traction in the snow - the rear tires are just too wide.

Here's how 'wide tires' were explained to me in one of my driving schools at Mid-Ohio. If you look at the 'physics' of tires, all tires have a contact patch with the road. The contact patch is simply the cars weight divided by the air pressure in the tires. If you're running the same air pressure in wide and narrow tires, you have the same amount of rubber contacting the road. The difference is that a wide tire has a narrow and wide patch that is ideal for cornering. A narrow tire has a long, narrow patch that is less prone to 'hydroplaning', or riding up onto the snow/rain. This is the reason you want to use the narrowest possible tire in the rear when driving in snow. The larger, softer sidewall doesn't transmit the axle torque to the road as directly as a smaller, stiffer sidewall, and so makes the wheel less likely to spin.
mdh is offline  
0
Reply With Quote
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 08:34 AM.




m5post
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