This is a further update for any R170 looking to upgrade to these awesome and classic wheels.
The local Mercedes dealership has confirmed that the rear 8.5x17 ET30 - Part number: B66020062 - is no longer available. I have asked Chris at alloywheelsdirect to see if he can somehow find these. The front 8x17 ET30 - Part number: B66020061 - is available but in limited numbers.
In the meantime, I've had a look at ebay and there are a number of refurbished original sets from apparently respectable sellers (100% feedback). These are mostly the 129 version, which are way too wide. There are only a few 124 version wheels but mostly sets of 4 equal wheels which makes sense since the 124 has a 4x1 instead of the 2x2 staggered setup.
The fact that they were made as sets of 4 equal wheels is not a small matter because the two wheels vary in shape and the result is not great (read on). Bearing in mind that these are 3-piece wheels, the 8" wide wheel is actually made up of a 6.5" inner rim plus a 1.5" outer rim (or lip), whereas the 8.5" wheel is made up of a 7.5" inner rim plus a 1" outer rim. This means that the narrower 8" has a deeper lip than wider 8.5", so the front wheels would be more 'deep dish' than the rear - which is bizarre - but these were made to fit as sets of 4, so this dilemma would have not come up.
There is a solution, I think, but someone would need to kindly check if I am completely off the tracks.
Switching the outer rims (lips)! If you switch the lips around, your would get a 6.5" inner rim plus a 1" outer rim, resulting in a 7.5"x17 ET36. The ET actually increases because of the reduced wheel width. This is as close as you can get to the stock setup (7.5x17 ET37).
The rear wheels would now be a 7.5" inner rim plus the wider 1.5" lip, resulting in a 9"x17 ET24. In this case, the ET is reduced because of the increased wheel width. This would not be as close to stock (8.5x17 ET34) as the front, but you would get the rear wheels sticking out 16mm from current position (approx 0.5"), which is within reasonable variance. Actually, just looking at the car you can see that space is tighter at the front, so it is advisable to keep as close to stock as possible especially at the front wheels. In any case, this is well within the fitting guidelines:
So you would get as close as possible to stock (especially at the front where it's tighter) and you would get the correct deep dish look (deeper at the rear wheels). Mind you, I think 1" is the smallest lip size offered by OZ, so at 1" front and 1.5" rear it is a really subtle deep dish look.
In any event, and if this is not possible, you could also ignore the stock 2x2 staggered look and go for a set of 4 equal wheels and save yourself a headache (
Looking at the fitting chart above, the 8" would fit perfectly in front but it would look rather thin on the rear, plus you would be better replacing the rear tyre from the stock 245 as it may be a little wide for the 8" wheel.
The 8.5" on the other hand sits perfectly on the rear wheels and the fitting chart suggests you could go as far as 8.5x18 ET25 in front, so you should be OK with 8.5 ET30 in theory. Plus, you get the thinner 1" OZ lip, which I think is nicer (especially having all 4 wheels the same).
I hope I can conclude this upgrade properly and let you know what the outcome is. I don't think there's one single SLK in Spain with these wheels on (nevermind 32AMGs).
Any ideas? Give us a shout!