4200/GS alternative space saver from a Mercedes SL R230

Messages
16
#81
I must stress the main reason I went with the Merc wheel is the same size tyre and rim diameter.
I don't think anything less than 17" will clear the brakes, and I didn't want to risk any tyre that is smaller in rolling circumference that could cause problems.
It is over 5 years now since I made the kit up, and it is a valid point regarding age, I recall one instance of the space saver (not sure if Merc or OEM) being inflated and found to be 'rotted'.
I've never used me, but my FD rims stick out right to the very outer lip of the front wings with no issues.
It's partly this age-of-the-rubber issue that is making me consider alternatives - including the similar but smaller width equivalent wheel from certain Mercedes later SLK's - narrower but almost the same circumference and weight limit.
Can one buy a new (= just manufactured) proper sized Space Master tyre (as per your set-up and the Maserati original) - and if so from a normal tyre depot or only from Mercedes or Maserati ? This would remove this worry. As an aside, I have (since new) a 1982 Renault Alpine A310 V6 that also came with an inflatable spare which I have never had to use and which I would be frigthened to use...
 

mjheathcote

Centenary Club
Messages
6,308
#82
When I was looking, at the time, the same size tyre was only used by Maserati, the Merc SL and also a model of Porsche 911 Turbo I recall.
I'm sure you can buy a tyre alone, at what cost though...

EDIT: Porsche Cayman S as well.
 

mjheathcote

Centenary Club
Messages
6,308
#83
Found this, a problem with a Porsche owner when he inflated his spare.
Might have to blow mine up for inspection...and hope if okay, I can deflate it again...

spare_tire.jpg
 
Messages
16
#84
Found this, a problem with a Porsche owner when he inflated his spare.
Might have to blow mine up for inspection...and hope if okay, I can deflate it again...

View attachment 53417
Wow ! That IS frightening ! I think even "wobble" bolts would be safer:);):(.

I dread to think what my 1982 Alpine one must be like - especially as it has lived all its life in the (rear) engine bay not far from the silencer.

If you do inflate yours in order to check its condition, I wonder whether you could (please...) try putting it (inflated) on each end of the car and checking the clearances (with the car back on the ground and moved enough to let the suspension settle, and then lock to lock and bouncing).
Tony
 
Messages
16
#85
A new question, please. I have a friend who has a 2007 Mercedes SLK which has the narrower SPACE MASTER I mentioned in my original post. I just asked him to measure its diameter and depth/width (uninflated) and he's replied 54.5 cms and 15 cms. I've then tried to see how the 54.5 cms diameter would fit into the wheel well of my 4200CC, expecting it to fit in easily and expecting to have gained significant space above it versus the wider SPACE MASTER the original subject of this whole topic. However 54.5cm doesn't want to drop down into the well at all, meaning that using the thinner wheel would gain me nothing at all - in fact it looks like it would stick up more. So here's my new question. Please could one of you with the wider SPACE MASTER (the one that's 185/60 17, Mercedes or OEM Maserati) tell me its overall diameter and depth/width (uninflated) so that I may compare how that would fit in my wheel well.
 

Masera

Junior Member
Messages
71
#86
Gents, success with the Merc space saver! Adapter arrived, installed and inflated spare just to make sure! As for the scissor lift, I am using an extra one I had from my 84 Biturbo! Now need to source humped carpet! Many thanks mjheathcote!!!
 

Attachments

Messages
16
#87
Thanks Masera for the excellent photos. I believe that the humped wheel cover carpet is part number 67243600. It's listed on the various Maserati parts sites but I'm not sure they have any in stock. Do let us know how you get on with finding one, please.

Regarding my own suggested alternatives, I've now been able to physically try my friend's narrower-but-virtually-the same-circumference-and-weight-classification ("145") on my 4200. To my surprise its bore is 67mm (and not 66.6mm), which meant that having removed the two 13mm bolts retaining the disc I was able to try it all the way on (flush to the hub face). Of course the holes do not quite line up (5x112 versus 5x108) but mounted like this there was slightly more clearance to the brake caliper than with the normal road wheel, and (in particular) the space saver wheel sits nicely compared to the wheel arch. I mention this because with the addition of 20mm of adapter thickness I am concerned about the space saver hitting the wheel arch with a bump in the road. Masera's fifth photo supports my fear...

In my investigations I found that it looks like the earlier Mercedes "185" space savers were alloys and the later ones were steel. Perhaps the alloy ones do have a 66.6mm bore? The earlier ones are of course, by definition, "earlier" - meaning an additional few years of shelf life used up - another reason for my looking into the later ones (be they in "185" or "145").

Given all the above, I have just purchased on eBay a wheel identical to my friend's one (part number 1714000202) and also five "wobble bolts". I am aware of all the violent internet debate about "wobble bolts" - opinions are at least as devided and devisive as the Brexit or Trump issues - but I thought it was worth at least investigating these before buying an adapter. Both my wheel and my "wobble nuts" should arrive (to me in France) about a week from now - when I will update my findings.

Cheers
Tony
 
Messages
6,308
#89
There is 4 mm difference between 112 and 108 PCD, the clearance holes in the space saver have to be huge to accommodate that much difference. If the hub used M12 bolts, and the wheel was originally designed for M14 bolts, with say a 15mm clearance hole, you still only then achieve a 3mm difference in PCD.
But our hubs are M14...
If you have offered up the space saver, can you see all 5 M14 tapped holes clearly? The clearance hole would have to be 18mm. Unlikely.
 
Messages
16
#90
There is 4 mm difference between 112 and 108 PCD, the clearance holes in the space saver have to be huge to accommodate that much difference. If the hub used M12 bolts, and the wheel was originally designed for M14 bolts, with say a 15mm clearance hole, you still only then achieve a 3mm difference in PCD.
But our hubs are M14...
If you have offered up the space saver, can you see all 5 M14 tapped holes clearly? The clearance hole would have to be 18mm. Unlikely.
Thank you for your very helpful comments. I understand and agree with everything you have said. But for the price of five "wobble nuts" I want to at least physically investigate this before buying an adapter, since if ever "wobble bolts" were usable I would prefer this to an adapter which it looks to me would throw the wheel too far out versus the wheel arch (and even if not would place additional stress on the wheel bearings like any other wheel spacer although I appreciate that for the hopefully short distance the spare would be used for this should have no ill effect.