hey Shawn D. and other OFFSET gurus

E28 technical advice asked and given! Troubleshooting, modifications and more.
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bobby in Derby City
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Joined: Feb 12, 2006 12:00 PM
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Post by bobby in Derby City »

want to know if I will be buying the correct wheel spacers for the 535iS. Punched in tha numbers for Shawn's dbase program and here's what I got:

16X7 OFFSET: 46mm BMW OEM Style 42 (one piece)
Tires: 225/60 (have not purchased yet)
using 20mm spacers

(FRONT/ BACK)

tire over: 0.4/0.4

BSw(in): 5.0/5.0

BSt(in): 5.5/5.5

FSw(in): 3.0/3.0

FSr(in): 3.4/3.4

GAP W-f: 0.45/~~~

GAP T-f: 0.24/~~~

GAP T-r: ~~~/0.46

I do not want to mess with the rear fenders if I do not have to. Do these numbers look like I should be okay all the way around or should I shoot for different sized spacers for the front and back. I like this style of wheel best (can't afford Rondell #58s), so I would like to use these wheel if all possible. I will be going with Bilstein sports and some lowering spring in the future too. Thanx in advance
fastpat
Posts: 1036
Joined: Feb 12, 2006 12:00 PM
Location: Travelers Rest, South Carolina

Post by fastpat »

[QUOTE="bobby in Derby City"]want to know if I will be buying the correct wheel spacers for the 535iS. Punched in tha numbers for Shawn's dbase program and here's what I got:

16X7 OFFSET: 46mm BMW OEM Style 42 (one piece)
Tires: 225/60 (have not purchased yet)
using 20mm spacers

(FRONT/ BACK)

tire over: 0.4/0.4

BSw(in): 5.0/5.0

BSt(in): 5.5/5.5

FSw(in): 3.0/3.0

FSr(in): 3.4/3.4

GAP W-f: 0.45/~~~

GAP T-f: 0.24/~~~

GAP T-r: ~~~/0.46

I do not want to mess with the rear fenders if I do not have to. Do these numbers look like I should be okay all the way around or should I shoot for different sized spacers for the front and back. I like this style of wheel best (can't afford Rondell #58s), so I would like to use these wheel if all possible. I will be going with Bilstein sports and some lowering spring in the future too. Thanx in advance[/QUOTE]

I have BMW Style 32 wheels in 16x7 (ET20) with 225/50-16 Yokohama AVS Sport tires mounted on them. My "is" is lowered via the BMW MTechinics springs, about 3/4 inch in the rear and 1 1/4 inch in the front. There's very little clearance between the lower sping perch on the front struts and the tires, and these tires have a rounded edge, a sharper edge would likely have less or no clearance.

Off hand, I'd say you're not going to be able to fit your wheel/tire combo with less than 25mm (one inch) spacers, which are too much in my opinion. I'm pretty conservative in what I ride on, and using 3-series wheels on an e28 with one inch spacers is looking for trouble. Just hanging the wheel/tire and the spacer will be a struggle everytime you remove and replace them.

Here's a photo of the wheels and tires on my e28:
Image
Shawn D.
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Location: Alpharetta, GA
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Post by Shawn D. »

[QUOTE="bobby in Derby City"]want to know if I will be buying the correct wheel spacers for the 535iS. Punched in tha numbers for Shawn's dbase program and here's what I got:

16X7 OFFSET: 46mm BMW OEM Style 42 (one piece)
Tires: 225/60 (have not purchased yet)
using 20mm spacers

(FRONT/ BACK)

tire over: 0.4/0.4

BSw(in): 5.0/5.0

BSt(in): 5.5/5.5

FSw(in): 3.0/3.0

FSr(in): 3.4/3.4

GAP W-f: 0.45/~~~

GAP T-f: 0.24/~~~

GAP T-r: ~~~/0.46

I do not want to mess with the rear fenders if I do not have to. Do these numbers look like I should be okay all the way around or should I shoot for different sized spacers for the front and back. I like this style of wheel best (can't afford Rondell #58s), so I would like to use these wheel if all possible. I will be going with Bilstein sports and some lowering spring in the future too. Thanx in advance[/QUOTE]

Hmm... plugging in 16x7, 46 offset w/ 20mm spacer (equivalent to 26mm offset), with a 225-section tire, I get different numbers:
Tire Over = 0.6
BSW (in) = 5.0
BST (in) = 5.6
FSW (in) = 3.0
FST (in) = 3.6
Gap WF = 0.45
Gap TF = 0.04
Gap TR = 0.26

This will work OK in the rear, but will be awfully close in front. Considering my statement on the "Read This First" page, "The gaps calculated by this spreadsheet are subject to errors in measurements and manufacturing tolerances. If a calculated gap is less than 0.20", you should consider the gap to be close to zero; if less than 0.10", you should consider that gap to be effectively zero." I'd say this will not work in front. As Pat said, you'd need a 25mm spacer.

IMO, a 25mm spacer is doable, but that would likely put your rear tires into contact with the rear fender. I understand that you don't want to mess with the rear fender, but it's really not a big deal.

I would not suggest mixing 25mm spacers in front with 20mm spacers in rear. While that would work technically, I'd be concerned that a simple mix-up during wheel swaps/rotation could lead to the wrong lug being put into the wrong hub, either making it penetrate too far or not enough.

I know the Rondells are expensive, but so were Center Lines when I was in high school. I hated waiting, but while my friends were going through sets of cheaper wheels, I was saving for the Center Lines for my '57 Chevy and I got them after I graduated -- I was glad I'd held off until I could afford them. I think you'd be glad if you wait to get the Rondells.

Also, I don't know if it was a typo, but you don't want 225/60 tires -- you want 225/50 tires.
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