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      11-03-2010, 12:20 PM   #1
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18" BBS RGR on M Coupe

I have a set of 18" RGRs for my 3.0si coupe that I plan on putting on my M Coupe. When I looked on tire rack only the 19" came up for the M coupe. When I change it to the 3.0si coupe 18" come up.

These are the specs of the ones that I have:

BBS RGR- Diamond Black Finish
1 pc Fully FORGED
18x8.5 all around et38 19.4lbs
Offset: 38mm
Backspacing: 6.22"
Bolt Pattern: 5-120

Thanks in advance
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      11-03-2010, 12:42 PM   #2
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You can definitely make them work.
The fronts are fine as is but you might want to add ~15mm spacers on the rear to flush them out a bit.

What are your tire sizes?
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      11-03-2010, 12:45 PM   #3
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Quote:
Originally Posted by inTgr8r View Post
You can definitely make them work.
The fronts are fine as is but you might want to add ~15mm spacers on the rear to flush them out a bit.

What are your tire sizes?
Thanks, perfect. I was thinking about spacers when I originally put them on the 3.0si since they aren't flush but never got around to it. I think it will really help on the M though.

The tires are stock size. 225 front 255 rear.
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      11-03-2010, 01:14 PM   #4
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yea, spacers will do the trick. make sure you get a set with extended lugs as your oe ones will be too short. or you can also go with a stud conversion..
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      11-03-2010, 01:17 PM   #5
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Thanks, what is the advantage to a doing a stud conversion? And what would be the additional cost?
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      11-03-2010, 02:33 PM   #6
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stud conversion makes swapping of wheels much easier as the wheels go right over the studs, as opposed to having to hold the wheel with 1 hand while trying to get the lugs through the hole.

studs also allow you to put on any width adapter w/o having to worry about the correct extended lug length (since the stud can accompany most spacers, and you just then tighten with the open lug).

for you, i'd say the latter is most relavent, especially if you also decide to run spacers on the front. just make sure, regardless of stud or extended lugs, you get wheel locks for those nice wheels. if you stick with lugs you can get extended RAD locks for the rears (too long for the front so just keep the ones you have now for front and remember to keep both wheel lock adapters in the car).

stud conversion will cost money so if you're not switching wheels out often, you're probably better off keeping to lugs =)
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      11-04-2010, 06:37 PM   #7
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I'm pretty sure handling will suffer w/ such a narrow rim for the rear...but if it's just looks than you'll probably need at least a 25mm spacer to make up for offset and width.

better off selling 2 wheels or keeping them as spares and purchasing 2 rear correct fit rgr's
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      11-04-2010, 07:45 PM   #8
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oops on my part; you are absolutely correct^ about a bigger spacer being necessary.
I was thinking 9.5" when I said 15mm would be OK.
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      11-04-2010, 09:40 PM   #9
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Yeah, the rear fitment for the 3.0si and the M are totally different. To reach roughly the same outer position as the M, a 15 mm spacer is correct. You'd effectively be making the wheel 8.5" ET 23.

As krnnerdboy said though, you'd be better off buying 2 RGRs of the correct fitment for the back.
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      11-09-2010, 03:20 PM   #10
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Hmm maybe I will sell them then and keep my eye out for a set of M-spec BBS on here in the classified forum.
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      12-14-2010, 04:28 AM   #11
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