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


Go Back   ZPOST > BMW Z4 Technical Talk > Wheels and Tires
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      08-09-2011, 11:44 AM   #1
3002 tii
Lieutenant General
3002 tii's Avatar
2272
Rep
12,559
Posts

Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT

iTrader: (99)

Garage List
Widest Front Tire on 18x8.5 et42?

Can anyone confirm what the widest tire I can run is, on a 18x8.5 et42 on a non-M, stock suspension? I'm willing to add negative camber if necessary, but am concerned that still might not address any strut side clearance issues. I do NOT want to run spacers up front.

Obviously 225/40 would work, but how about 255/35?
__________________
Follow for latest mods
Appreciate 0
      08-09-2011, 12:17 PM   #2
v3.0si
Lieutenant
v3.0si's Avatar
United_States
17
Rep
409
Posts

Drives: '08 Z4C 3.0si
Join Date: Sep 2010
Location: midwest

iTrader: (2)

this topic sounds familiar...

by chance, have you measured your current strut-side clearance? it might be a good starting point for figuring this out.
__________________
| v3.0si | | '08 Z4Coupe 3.0si | BMW Aero | BMW Performance |
Appreciate 0
      08-09-2011, 12:27 PM   #3
3002 tii
Lieutenant General
3002 tii's Avatar
2272
Rep
12,559
Posts

Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT

iTrader: (99)

Garage List
Quote:
Originally Posted by v3.0si View Post
this topic sounds familiar...

by chance, have you measured your current strut-side clearance? it might be a good starting point for figuring this out.
Good memory =)

But I'm just getting too many varying opinions on the topic. Consensus seems camber will help with fender issues, but nobody can confirm strut side clearance w/o having to use a spacer.

Will do that this weekend, but my concern is that on paper 255's might fit but on hard cornering or on the track, it may still rub...
__________________
Follow for latest mods
Appreciate 0
      08-09-2011, 01:53 PM   #4
v3.0si
Lieutenant
v3.0si's Avatar
United_States
17
Rep
409
Posts

Drives: '08 Z4C 3.0si
Join Date: Sep 2010
Location: midwest

iTrader: (2)

i didn't want to wait, so i'm using mine as a base line...

alright. maths.

8.0" et34 w/ 225/40 tread is producing ~25mm clearance from the strut to the inner edge of the tire on full left-hand lock (LF wheel was used for measuring).

if i were to install your wheel, the inner edge would be 14mm closer to the strut.

and an additional 15mm for a 225 --> 255 tread (255-225=30... 30/2=15).

~25mm definite clearance compared to 29mm loss = ~4mm deflection of the tire on the strut. and this is assuming the sidewall cross-section doesn't change.

methinks a minimum of a 5mm spacer is required, maybe bigger. hell, at ~4mm, a 245 tread may still rub without a spacer.

dubbe, i think you're hosed. but i really want you to prove all this wrong... i would love to put some 255 tread up front!
__________________
| v3.0si | | '08 Z4Coupe 3.0si | BMW Aero | BMW Performance |
Appreciate 0
      08-09-2011, 02:01 PM   #5
v3.0si
Lieutenant
v3.0si's Avatar
United_States
17
Rep
409
Posts

Drives: '08 Z4C 3.0si
Join Date: Sep 2010
Location: midwest

iTrader: (2)

i'm surprised you haven't done a test fit with one of your rears yet. jack it up and flip 'em already!
__________________
| v3.0si | | '08 Z4Coupe 3.0si | BMW Aero | BMW Performance |
Appreciate 0
      08-09-2011, 02:10 PM   #6
3002 tii
Lieutenant General
3002 tii's Avatar
2272
Rep
12,559
Posts

Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT

iTrader: (99)

Garage List
Quote:
Originally Posted by v3.0si View Post
i'm surprised you haven't done a test fit with one of your rears yet. jack it up and flip 'em already!
I'm not that lazy, ha... I have 225 on all 4's now. Will report back with my findings...
__________________
Follow for latest mods
Appreciate 0
      08-09-2011, 02:33 PM   #7
v3.0si
Lieutenant
v3.0si's Avatar
United_States
17
Rep
409
Posts

Drives: '08 Z4C 3.0si
Join Date: Sep 2010
Location: midwest

iTrader: (2)

ohhh... i see.



and i've always wanted to use this...

__________________
| v3.0si | | '08 Z4Coupe 3.0si | BMW Aero | BMW Performance |
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 02:53 AM.




zpost
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