[W126 Coupe] RE: Wheel Fitment Problem

[Sam Sisic]

Jim,

Just note that a 10.5 inch wheel width is measured on the inside of the rim where the tire makes the seal. The overall width of that wheel is probably closer to 11 inches.
The other interesting thing I learned from Luke at Tire Rack is that the 275mm tire width number referenced below is the sectional width of the tire, not the tread width... When clearance issues are concerned, tread width is sometimes more relevant as this is the outermost width of the tire. Depending on the manufacturer of the tire, the tread width will vary up to a half inch within the same "tire Size".
I would also stay close to the overall diameter of the tire to stock which is aprox. 25.5"... 275/40-17 would be good. The 285/40-17 you were planning on using have an overall diameter of 26"... This would throw off your speedometer.
I found these links below from The Tire Rack very helpful in understanding wheel and tire sizes and offsets...  Sometimes, a picture is worth a thousand words.

http://www.tirerack.com/tires/tiretech/general/size.jsp
http://www.tirerack.com/wheels/tech/offset.jsp

Leave the B.F. Hammer for something a little less accurate like a Rolex watch...

Sam
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Message: 5
Date: Mon, 24 Jan 2005 08:22:37 +0000
From: "Sharan Bains" <sharanbains at hotmail.com>
Subject: RE: [W126 Coupe] Wheel Fitment Problem - HELP PLEASE!
To: mbcoupes at mbcoupes.com
Message-ID: <BAY17-F184E5AB8E7FA1A98FB4D52BF850 at phx.gbl>
Content-Type: text/plain; format=flowed

Jim,

I think you'll need to do the following :

- use 20mm spacers in the rear

- fit 275's and not 285's. Tyre of 275 is more than you need on a 10.5 inch 
wheel as the wheel is approx 267mm.

- from memory, you'll need to use specific bolts with the BBS wheels, since 
they have a recessed centre and without spacers require bolts wth very small 
shaft lengths. With 20mm spcaers you may only need botls which have a 55mm 
shaft length - you'll have to work this out by measuring up the bol shaft 
that protudes from the rear of the wheel when inserted. In summary, don't 
work to the MB bolt formula of 40mm + spacer width.

I don't think that should be too much of a problem once you have the 20mm 
hubcentric spacers. Shame, as I sold a set of original H&R 20mm spacers two 
weeks ago for about 60USD.

To give you an idea, the original AMG wheels (as I have on my 560) are 10 x 
17 et 17. Now if you run 20mm sacers, your et will be down to 18, which 
should work, as you are only running an extra half-inch of wheel, which in 
reality is 0.25 inches - since I think the only concen is going to be the 
wheel rubbing on the inner well, not the outer fender lip.

With 10.5 width and ET 18 (38-20), you'll have an extra 6.35mm of metal on 
the inner side in direct comparison to my 10 width with ET 17, plus the 
extra millimetre of offset means you are a total of 7.35mm closer to the 
inner wheel well than my AMG's. Now Satish is running 10 inch wheels with ET 
25mm - that's 8mm closer to the inner wheel well than my AMG's and that 
works. So I fairly confident your BBS's will work with 20mm spacers and 275 
tyres.

If not, there's always the B.F. hammer one can utilise...

I wouldn't change the outer rims on the BBS to reduce width - as then you'll 
lose the deep dish effect whch is what those wheels are all about. You need 
deep dishes on the rear wheels....

talbir






>From: JR560SEC at aol.com
>Reply-To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>To: mbcoupes at mbcoupes.com
>Subject: [W126 Coupe] Wheel Fitment Problem - HELP PLEASE!
>Date: Sun, 23 Jan 2005 20:47:27 EST
>
>Greetings, everybody---------please put on your "thinking caps" for this 
>one:
>
>After hearing for years that just about ANY oversize wheel width could fit 
>on
>the rear of the SECs (with proper offset, at least), I guess I just went 
>too
>far.  I was attempting to fit some 3-piece BBS RS 10.5 x 17 ET 38 wheels on
>the rear of my 1990 560SEC.  The WHEEL LIP (not the tire; I don't even know
>about that yet) strikes the inside of the wheel well when the suspension is 
>fully
>extended, and when the suspension is compressed, it continues to strike 
>until
>compressed to lower than normal ride height.  When viewed from the driver's
>side, the area the wheel lip strikes is from 9 o'clock (straight ahead) to 
>about
>11:30 (almost straight up).  At that point, there is a steel reinforcement
>piece behind the sheet metal, at the bottom of which is the rubber bumper 
>which
>limits suspension compression.
>
>The clearance problem looks pretty bad at max. suspension 
>extension----could
>be about 3/8-inch (10 mm) interference, maybe more.  It looks like most of 
>the
>necessary clearance could be achieved using a B.F. hammer, except at max.
>suspension extension, at which point the aforementioned steel reinforcement
>behind the wheel well sheet metal is present and would prevent 
>"clearancing."
>
>I plan to use 285/40-17 tires, if they can be made to fit.  The wheels are
>sufficiently wide that the tires should not protrude much beyond the WHEEL 
>lip.
>Still, I can't yet tell at what other areas within the wheel well the tire
>might encounter clearance problems.
>
>The fender lip is rolled from the factory from 12 o'clock to the rear but 
>not
>toward the front.  I will roll the fender if necessary to clear the tire.
>Since these are 3-piece modular wheels, the "fallback" alternative is to 
>buy two
>new inner rings to reduce the wheel width to 10 inches (for ET 32 offset) 
>or
>even 9.5 inches (for ET 25 offset)---but I'd rather stick with the present
>rings, if possible.  Where on earth would I find a couple of inner rings, 
>anyway?
>  I also can use spacers, though at this point I can't tell if I'd have
>outside clearance problems anyway, even without spacers, once the tires are 
>mounted.
>
>For what it's worth, the front has 8.5 x 17 ET 13 BBS RS with 235/45-17s
>which fit with no clearance problems of any sort and, of course, no spacers 
>with
>that small an offset.
>
>My questions:
>
>1.    Has anybody successfully used 10.5 x 17s on a non-widebody SEC?
>
>2.    If so, what wheel offset (or offset/spacer combo) did you have?
>
>3.    What is the max. tire width anybody has used, AND the accompanying
>wheel width?
>
>4.    If I'm in uncharted territory, does anybody have a handful of
>hubcentric spacers of varying widths (say from 6 to 15 mm) plus lug bolts I 
>could
>borrow, for trial fitment?
>
>Thanks so much in advance, everybody, and I'll be eager to hear your 
>counsel
>with this messy problem.
>
>Jim Rothrock, Windermere, Florida
>The MB Coupes Website!
>W126 SEC Mailing List
>Postings remain property of MB Coupes, L.L.C.




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