E90Post
 


TireRack
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > All-Wheel-Drive (Xi / xDrive) Talk > will 235/40/18 work out on the xi?



Reply
 
Thread Tools Search this Thread
      11-07-2012, 05:23 PM   #1
bob.g
Lieutenant
 
Drives: 2006 325xi
Join Date: Sep 2009
Location: montreal

Posts: 591
iTrader: (1)

will 235/40/18 work out on the xi?

i have a 2009 bmw 335xi with the 18 style 189 wheels.

i need winter tires and saw some 235/40/18 at a good price but when i check the offset calculator the rears seem to be above 1% (Was like 1.34 i think). Am i doing something wrong? i seem to recall someone saying if the tires are the same front to back, it wont be a problem with the xi system as long as they fit (and that size does fit based on posts ive seen, i just cant seem to find posts of ppl using them on an xi). Thanks!
bob.g is offline  
0
Reply With Quote
      11-07-2012, 07:37 PM   #2
Priority 1
Private First Class
 
Priority 1's Avatar
 
Drives: e92 335xi
Join Date: Mar 2009
Location: Philadelphia

Posts: 157
iTrader: (0)

What you need to worry about is the difference in rolling diameter between each of the tires mounted on the car at the same time to protect the transfer case, and the difference in rolling diameter between the new tire size and stock to keep the speedometer readings consistant.

People run square tires on staggered wheels with X-drive a lot and I am not aware of any issues with that. The only difference will be in appearance of the angle of the sidewalls which some people care about, and a slightly increased (~.200") section width (distance from sidewall to sidewall) in the rear versus the front. I haven't found anything that tells me that this affects the rolling diameter.

That difference you calculated tells you that the difference in rolling diameter from stock to winter will affect the speedometers reading. Since those wheels are quite a bit taller than stock they will travel further per rotation and your actual speed will increase relative to what the speedometer says with the stock tires. I found that the stock speedometer calibration reads higher than actual and so this may push your speedometer to reading closer to the actual speed. Make sure to keep an eye on it though and try to check it with a radar sign if you have those up north, and remember the delta between observed and actual speeds.

Off topic but in Canada I'd think you'd prefer narrower tires to help in deeper snow and 225/40R18 should be cheaper all around and keep the speedo consistant from stock to winter.

Last edited by Priority 1; 11-07-2012 at 07:45 PM.
Priority 1 is offline   United_States
0
Reply With Quote
      11-07-2012, 09:45 PM   #3
Raptor001
Lieutenant
 
Drives: 2009 335i xDrive
Join Date: Aug 2010
Location: Colorado Springs

Posts: 415
iTrader: (3)

I am running 225/45/18 front and 245/40/18 rears non run flat winter tires on stock 189s. As long as your within 3% of stock diameter, you will be fine.
__________________
E90 N54 LCI 335i xDrive//Vishnu//Wedge//K&N// VRSF//Fortune Auto//Swift//Whiteline//TC Kline// Ultra Racing//ECS//Pagid//Carbotech//G2//DTEC// Apex//Hankook
Raptor001 is offline  
0
Reply With Quote
      11-07-2012, 10:00 PM   #4
bob.g
Lieutenant
 
Drives: 2006 325xi
Join Date: Sep 2009
Location: montreal

Posts: 591
iTrader: (1)

really, its as much as 3%? i remember reading 1% tops.
bob.g is offline  
0
Reply With Quote
      11-08-2012, 02:42 PM   #5
wdeerfield
A family of bimmers
 
Drives: 2009 e90 2011 f10
Join Date: Jan 2012
Location: Clifton Park, NY

Posts: 3,095
iTrader: (0)

keep it to 1%. 235/40/18 on a 8 and 8.5 should have the same diameter i believe. i have 235/40/18 on my 18x8.5s for summer and 225/45/17 on my 17x8s for winter
__________________

2009 MBM 328| ZPP | ZSP | ZCW | CA | 6FL | NAV | XENONS | 18x8.5 VB3s ET30/25
2011 Jet Black 535i xdrive | ZPP | ZSP | ZCW | 6FL | NAV | 331s Square
wdeerfield is offline   United_States
0
Reply With Quote
      11-08-2012, 05:03 PM   #6
bob.g
Lieutenant
 
Drives: 2006 325xi
Join Date: Sep 2009
Location: montreal

Posts: 591
iTrader: (1)

Quote:
Originally Posted by wdeerfield View Post
keep it to 1%. 235/40/18 on a 8 and 8.5 should have the same diameter i believe. i have 235/40/18 on my 18x8.5s for summer and 225/45/17 on my 17x8s for winter
yeah that's what i have, 18x8 front which is fine, its the 18x8,5 rear on this tire size that gives me problems.

when i check the calculator, if i set 8.5 wheel width inches, and 37 mm offset (i set that for both "current" and "new") then choose the original tire size of 255/35/18 and then put the NEW tire size of 235/40/18 and it gives a percent difference of 1.472%. it seems any "original" tire size i put for the rear always goes above 1% when trying to compare it to 235/40/18. Am i doing it wrong? i hope i am..will save me a lot of problems trying to find other tires.
bob.g is offline  
0
Reply With Quote
      11-08-2012, 06:52 PM   #7
Priority 1
Private First Class
 
Priority 1's Avatar
 
Drives: e92 335xi
Join Date: Mar 2009
Location: Philadelphia

Posts: 157
iTrader: (0)

Quote:
Originally Posted by bob.g View Post
yeah that's what i have, 18x8 front which is fine, its the 18x8,5 rear on this tire size that gives me problems.

when i check the calculator, if i set 8.5 wheel width inches, and 37 mm offset (i set that for both "current" and "new") then choose the original tire size of 255/35/18 and then put the NEW tire size of 235/40/18 and it gives a percent difference of 1.472%. it seems any "original" tire size i put for the rear always goes above 1% when trying to compare it to 235/40/18. Am i doing it wrong? i hope i am..will save me a lot of problems trying to find other tires.
Did no one read my response? If you are putting 235/40/18 on all four wheels there is a negligible difference in rolling diameter and you are fine in terms of your all wheel drive. Just keep in mind you are going to be driving faster than the speedo indicates, and could get a ticket because of that difference you calculated. If you want to keep the same speedo reading and get better deep snow traction, mount 225/40R18 on all four wheels.
Priority 1 is offline   United_States
0
Reply With Quote
      11-08-2012, 06:57 PM   #8
bob.g
Lieutenant
 
Drives: 2006 325xi
Join Date: Sep 2009
Location: montreal

Posts: 591
iTrader: (1)

Quote:
Originally Posted by Priority 1 View Post
Did no one read my response? If you are putting 235/40/18 on all four wheels there is a negligible difference in rolling diameter and you are fine in terms of your all wheel drive. Just keep in mind you are going to be driving faster than the speedo indicates, and could get a ticket because of that difference you calculated. If you want to keep the same speedo reading and get better deep snow traction, mount 225/40R18 on all four wheels.
haha sorry P1. i did read it, speedo isnt an issue for me, and id do 225 but everyone jumps on that size locally so i can score some used 235's dirt cheap.. but i wanted to double check to see the % diff since i keep hearing 1%+ is bad, and when i checked it, it was over 1%.
bob.g is offline  
0
Reply With Quote
      11-08-2012, 07:01 PM   #9
wdeerfield
A family of bimmers
 
Drives: 2009 e90 2011 f10
Join Date: Jan 2012
Location: Clifton Park, NY

Posts: 3,095
iTrader: (0)

obviously there will be a difference over the 255.. but all four wheels for the winter are the issue, front and rear. 235s front and rear will be fine. speedo will read 60 and youll be doing 59mph. 235/40 is .5inches taller than stock so thats why you see the % difference.
__________________

2009 MBM 328| ZPP | ZSP | ZCW | CA | 6FL | NAV | XENONS | 18x8.5 VB3s ET30/25
2011 Jet Black 535i xdrive | ZPP | ZSP | ZCW | 6FL | NAV | 331s Square
wdeerfield is offline   United_States
0
Reply With Quote
      11-08-2012, 07:05 PM   #10
Priority 1
Private First Class
 
Priority 1's Avatar
 
Drives: e92 335xi
Join Date: Mar 2009
Location: Philadelphia

Posts: 157
iTrader: (0)

Ok so now that we have more information...make sure that the tread depth on those USED tires are identical. If they are substantially different, say 2 or more 32nds of an inch, then you could get into a problem with excessively wearing your transfer case.

If they have the same tread depth then you are good to go. I actually have the same issue right now in that i need to replace my LM-25 blizzaks that i got in 225/255 stock staggered sizes. They don't make those sizes anymore so I'm trying to warm up to the idea of the same tire on all wheels. I just like the look of the 255 winters in the back!

Last edited by Priority 1; 11-08-2012 at 07:16 PM.
Priority 1 is offline   United_States
0
Reply With Quote
      11-08-2012, 07:49 PM   #11
Chrisred
Captain
 
Chrisred's Avatar
 
Drives: BMW 335xi coupe
Join Date: Jan 2010
Location: Montreal, Canada

Posts: 738
iTrader: (0)

I just installed 235/40/18's all around for my winters on oem 189's. Feel great. I don't get that clunk anymore I used to get before running 235/35/19 & 265/30/19 when I was switching gears......

I went with 235's cause the 8.5 rears would of been tight with a 225
__________________
JB4 cp-e IC AMS exhaust BMS DCI AR DP's METH
19" VMR VB3 Stoptech BBK TC KLINE VORSHLAG
Chrisred is offline   Canada
0
Reply With Quote
      11-08-2012, 07:53 PM   #12
bob.g
Lieutenant
 
Drives: 2006 325xi
Join Date: Sep 2009
Location: montreal

Posts: 591
iTrader: (1)

ah ok. Thanks guys. so i guess ill go with these.
bob.g is offline  
0
Reply With Quote
      01-01-2013, 08:33 AM   #13
07lilredwagon
Lieutenant
 
07lilredwagon's Avatar
 
Drives: 07 328 wagon
Join Date: Dec 2012
Location: New York

Posts: 525
iTrader: (0)

Quote:
Originally Posted by Priority 1 View Post
Ok so now that we have more information...make sure that the tread depth on those USED tires are identical. If they are substantially different, say 2 or more 32nds of an inch, then you could get into a problem with excessively wearing your transfer case.

If they have the same tread depth then you are good to go. I actually have the same issue right now in that i need to replace my LM-25 blizzaks that i got in 225/255 stock staggered sizes. They don't make those sizes anymore so I'm trying to warm up to the idea of the same tire on all wheels. I just like the look of the 255 winters in the back!
Are these cars seriously THAT sensitive to tread depth variations!!!!!????? REALLY?? when we are talking about 32nds of an inch that is hard to see let alone calculate....this seems excessive to me from a common sense point of view. A car should not need this kind of fiddly attention....

The question for me is "why". is it because the drive shafts are rigidly mounted between the front drivers and the rear drivers through the transfer case?...Thats the way it looks from underneath the car. I would think BMW would have added some parameters to the design, but maybe they already did and their parameters are what they feel are acceptable at plus or minus 1 percent. That's tight!... Is this the same for other all wheel drive vehicles out there?

So if my rear tires are worn more than my fronts, for instance, are you saying that I will not be able to get close to the wear indicators on those rear tires if the fronts are in better shape? I would like to feel that I have gotten good use out of the tires and not have to worry about my transfer case blowing up or shredding its internal organs.

without re reading through the post...what is that magic number for the difference in tire diameter?.....1/16"?, 1/8"?, 1/4"?

So I guess I cant go with Cragar mags in the rear and skinnys up front?...My redneck BMW dreams shot to heck

seriously, I dont mind running the same size tire at all 4 corners...nice to know that we could, though....I guess thats for the 2 wheel drive crowd, eh?

sorry, Im a little punchy after last night!

JP
07lilredwagon is offline  
0
Reply With Quote
      01-02-2013, 10:23 AM   #14
Rich_NYC
Private
 
Drives: e90 328xi
Join Date: Nov 2012
Location: Queens

Posts: 78
iTrader: (1)

I just got these http://www.e90post.com/forums/showthread.php?t=785853 for my 328xi 19" 8.5 front 19" 9.5 rear et35 . what tires would be ideal for them ? ( have 07 328xi ) would 225/35/19 front and 245/35/19 back ( with 20mm spacers on the back ) give any problems ? thanks

Last edited by Rich_NYC; 01-02-2013 at 11:08 AM.
Rich_NYC is offline  
0
Reply With Quote
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 11:48 PM.




e90post
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