Wheel offset questions

Gary Knox

Gary Knox

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I am interested in a set of 2 piece 16" wheels which will need to have the width of the inner section of the barrels changed. I need to know the opinion of those who KNOW these cars (like I knew the previous P-928's) regarding what will work on my '74 model year car.

For the rear, I'd can make it 8" wide, with an offset of 13 mm. I think that is workable - is it?
Another rear option would be 8.5" with a 20 mm offset. Workable? I could be happy with either of these.

For the front, I'd have a 7.5" with an offset of 7 mm. Is that workable. I don't think a 7" wheel with offset of 1 mm is workable - is that right? Of course another option would be the 8" with the 13 mm offset - workable?.

I'd prefer the 8" or 8.5" rear and a 7.5" front.

I'd like to use 225/50 on the rear and 205/55 on the front.

Further info: I'll have Carl Nelson lowering springs, camber plates, and will be rolling the fenders - certainly fronts, but probably rears as well. I've also removed the ~1" strut plates that were OE on the US cars for bumper/headlight height for Trans Dept regulations.

EXTREMELY thankful for your help.
 
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I run BMW style 61 wheels that are 7.5" wide with a 20mm offset. In the front, they are just inside the fenders. Like you, I have Carl Nelson springs and I run adjustable camber plates. Front fenders are rolled. I'd think a 7.5" with 7mm offset or an 8" wheel with 13mm offset (like you mention) would stick out of the fenders, which wouldn't be very attractive and probably even rolling the fenders would not be enough to prevent rubbing.
my30cs.jpg
 
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I'm using a 8" (+20mm offset) wide wheel up front with a 215/45/18 tire. Front end is lowered on a custom coilover suspension setup.

On the rear, I'm running 9" (+22mm offset) wide wheels that's lowered on factory CSL rear springs. Using a 245/40/18 tire.

Car is a '70 2800CS with BMW Style5/BBS RC060/061. Fenders rolled at all 4 corners. Hope this is helpful.

(edited for correction)
 
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Gary,

I think you should get some 16" numbers for the front. You just need something that fits with or without a spacer as the starting point for your math. I think verde2002 is running 16x7.5 up front. Also Wise9uy is running 16's. He recently raised a point about the angle of the front strut, and how a 17" or 18" will clear the strut better. Once you have a 16" that fits you can have someone measure the distance to the strut and fender, fiddle with the width and offset calcs from there.
 
MPowerE9 said:
I'm using a 8" (+20mm offset) wide wheel up front with a 215/45/18 tire. Front end is lowered on a custom coilover suspension setup.

On the rear, I'm running 9" (+22mm offset) wide wheels that's lowered on factory CSL rear springs. Using a 245/40/18 tire.

Car is a '70 2800CS with BMW Style5/BBS RC090. Fenders rolled at all 4 corners. Hope this is helpful.
Click to expand...

Could you possibly post a pic? I would expect that the rear could still come out just a bit more with that set-up?
 
Who can verify whether the rear wheel mounting width for the brake drums on the 2800 CS are the same distance from the centerline of the car as they are on the '74 disc brake 3.0 CS? I seem to remember there was a change.

Thanks again for any help.
 
MPowerE9 said:
Forgot to add that the 2800CS has a rear disc brake conversion executed by the PO.
Click to expand...

Thank-you for the pics of the rear wheel... what a tease! I now want to see the whole car :D Looks like a sitting ride! With the rolled fenders do you get any rubbing? Was there much rubbing before rolling?
 
sreams said:
I run BMW style 61 wheels that are 7.5" wide with a 20mm offset. In the front, they are just inside the fenders. Like you, I have Carl Nelson springs and I run adjustable camber plates. Front fenders are rolled. I'd think a 7.5" with 7mm offset or an 8" wheel with 13mm offset (like you mention) would stick out of the fenders, which wouldn't be very attractive and probably even rolling the fenders would not be enough to prevent rubbing.View attachment 21261
Click to expand...

I forgot to mention, those style 61's with lower profile wheels than originally used on the E38 look really good on the E9. I think this is the first modern wheel I have seen to work really well with the car, probably due to the Alpina-esque radial spoke design... just with a nice modern twist and gentle concave... Nice!
 
MPowerE9 said:
I'm using a 8" (+20mm offset) wide wheel up front with a 215/45/18 tire. Front end is lowered on a custom coilover suspension setup.

On the rear, I'm running 9" (+22mm offset) wide wheels that's lowered on factory CSL rear springs. Using a 245/40/18 tire.

Car is a '70 2800CS with BMW Style5/BBS RC090. Fenders rolled at all 4 corners. Hope this is helpful.
Click to expand...

I thought the RC090 BBS Style 5s were 17"

However, customizing with new lips and barrels could be just about anything. :)

Pics please.
 
kbken62 said:
I thought the RC090 BBS Style 5s were 17"

However, customizing with new lips and barrels could be just about anything. :)

Pics please.
Click to expand...

RC's are a two piece wheel, so the lip/barrel is all one piece. You can't really change the lips, and changing the hoop is kind of pointless as you can just buy a different size RC (unless you find used barrels). RC090's are by far the most common. There are thousands floating around from factory e39's. If you want custom lips, you have to cut the lip off and have a custom one spun to match. An easy way to find a cheap set of 18's is to look on CL for $1,000 beater e38's.

RC040: 17x7.5
RC090: 17x8
RC091: 17x9
RC060: 18x8
RC062: 18x9
 
kbken62 said:
I thought the RC090 BBS Style 5s were 17"
However, customizing with new lips and barrels could be just about anything. :)
Pics please.
Click to expand...

I'm told that it's an uncommon version of the Style5 wheel. Found on the Euro-model E38 Sport edition. The wheels have not been re-barreled.

20161001_131448.jpg
 
MPowerE9 said:
I'm told that it's an uncommon version of the Style5 wheel. Found on the Euro-model E38 Sport edition. The wheels have not been re-barreled.

View attachment 21354
Click to expand...

Very nice stance. Now that I see the 18's on the E9 and with that amount of lowering, they suit the car superbly. So under the cap it says RC090 and it is 18"? I tend to agree with @Markos that the 18" setup are the 060/061 wheels but am confused if yours say RC090. They certainly don't look rebarrelled because if they were, then you would have to have a stepped lip to account for the extra inch diameter.
 
BBS 3 piece wheels of any size have not been fitted to any BMW cars since the factory equipped BBS RS 415mm TRX's on the mid 80's Euro M635csi's.
 
WISE9UY said:
Very nice stance. Now that I see the 18's on the E9 and with that amount of lowering, they suit the car superbly. So under the cap it says RC090 and it is 18"? I tend to agree with @Markos that the 18" setup are the 060/061 wheels but am confused if yours say RC090. They certainly don't look rebarrelled because if they were, then you would have to have a stepped lip to account for the extra inch diameter.
Click to expand...

You're right. They are the 2pcs wheel RC 06* in 18x8 and 18x9. Factory BMW wheel made by BBS.

I stand corrected. Thx WISE9UY! Appreciate the comments.
 
Markos said:
RC's are a two piece wheel, so the lip/barrel is all one piece. You can't really change the lips, and changing the hoop is kind of pointless as you can just buy a different size RC (unless you find used barrels). RC090's are by far the most common. There are thousands floating around from factory e39's. If you want custom lips, you have to cut the lip off and have a custom one spun to match. An easy way to find a cheap set of 18's is to look on CL for $1,000 beater e38's.

RC040: 17x7.5
RC090: 17x8
RC091: 17x9
RC060: 18x8
RC062: 18x9
Click to expand...

I would be interested in a pair of RC091s.

Would you know which vehicle this were available on? Also if anyone still sells them new?
 
MPowerE9 said:
I'm using a 8" (+20mm offset) wide wheel up front with a 215/45/18 tire. Front end is lowered on a custom coilover suspension setup.

On the rear, I'm running 9" (+22mm offset) wide wheels that's lowered on factory CSL rear springs. Using a 245/40/18 tire.

Car is a '70 2800CS with BMW Style5/BBS RC060/061. Fenders rolled at all 4 corners. Hope this is helpful.

(edited for correction)
Click to expand...

Another question: So is it factory CSL springs all round? Where did you get them? Thank-you!
 
MPowerE9 said:
The rear suspension is the CSL progressive rate coil spring sold by W&N. Thee fronts are a custom coilover suspension setup.
Click to expand...

You can probably see the next question coming... what brand is the custom coilover and from where is it available? I have only see KW doing a set for the E9. Also, that rear end looks fairly low even for CSL... is that just straight spring swap to get that height? Thank-you!
 
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