4200/GS alternative space saver from a Mercedes SL R230

tonycharente

Junior Member
Messages
34
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
6,406
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
6,406
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
 

tonycharente

Junior Member
Messages
34
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
 

tonycharente

Junior Member
Messages
34
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
75
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

tonycharente

Junior Member
Messages
34
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
 

mjheathcote

Centenary Club
Messages
6,406
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.
 

tonycharente

Junior Member
Messages
34
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.
 

tonycharente

Junior Member
Messages
34
Update and a key new question please..

This week I received my "145" (narrower) SPACE MASTER wheel and my set of "wobble bolts", and I was able to try them together on my 4200. This immediately proved that "mjheathcote" was absolutely entirely right, since I was not able to align the holes sufficiently to start more than 3 of the 5 bolts. He had suggested that the clearance holes in the wheel would have to be 18mm - mine are 17mm - Q.E.D.

However I also discovered that even if the bolts had fitted through all the holes I would not have been able to use them. My wheel had come with its own kit of shorter bolts (steel spare wheel replacing alloy) and I noticed that these were "ball seat" (AKA "radius","spherical" or "rounded") and not "conical" (AKA "cone" or "taper"). Wobble bolts are almost invariably "conical" and those that I had purchased certainly are. And it is very unsafe to use conical bolts in ball seat holes...

My subsequent Internet searches lead me to believe that all recent Mercedes wheels are "ball seat" and that they use two different versions - those with M12 bolts (like my "145" one) use "R12" ball seats - (i.e the radius of the spherical ball shaped holes is 12mm) - whilst those with M14 bolts have R14 (= 14mm radius) ball seats. Hoping that this is not all news to you, my question for those having adopted the Mercedes "185" (original width) spare solution is: are your ball seats "R12" or "R14", please? And also what is the diameter of the clearance hole (e.g. 17mm?)

Just in case this actually is news to any of you, the way to tell the radius of your ball seats is to push the edge of a washer or coin of the appropriate diameter (24mm or 28mm) into the seat in the wheel hole to see which fits nicely. Appropriate 24mm coins are UK 10p (just slightly bigger), US quarter, Canadian 25 cents, Euro 50 cents. Appropriate 28mm coins are UK £2 (just slightly bigger) and Canadian 2 dollars. (I don't have a full set of US coins...).

Once again, many thanks for your help,
Tony
 
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tonycharente

Junior Member
Messages
34
All done ! : here are my updated contributions...

I found a cheaper source for the adapter - one that doesn't insist on selling you two... It's a French company that has them made in 7075 alloy in Germany - very nicely made - the delivered price for one shipped from Germany to the French company and then on shipped to me (in France also) was 59,90 Euros (about £53) - this included the five bolts to attach the adapter to the hub, but no other bolts or studs. I had no need of either of these latter - see below. Shipped to the UK would obviously be a bit more. I'm not sure if I'm allowed to post their website ? Or PM me ? I have no connection with either company.

My smaller width wheel (from certain Mercedes SLK's, tyre size 145/70-17 92P), came with a set of five "ball seat" short bolts (supplied as a part of the kit by Mercedes to use with the steel space saver instead of the full size alloys) so I was able to use these to bolt it to the adapter.

My wheel was made in 2008 - I inflated it in order to make sure the rubber still looks good. Inflated it's exactly the same diameter as the normal road wheels. I have seen the "full width" ones for sale made in 2010.

My narrower wheel fits a little lower down in the 4200's spare wheel well (the rim is narrower too - 4.5x17 versus 6.x17), leaving more stowage space and perhaps making buying the humped boot floor less necessary. The boot floor will be my next project.

My adapter is only 18mm thick. There are absolutely no clearance issues with this narrower wheel - nor would there have been with a 20mm thick adapter.

I will try to attach various photos.
20190208_165358.jpg20190210_150921.jpg20190210_153725.jpg20190210_154924.jpg20190210_160424.jpg20190210_173735.jpg

Finally another VERY BIG thanks to MJHeathcote for his excellent original article, without whom I would have got nowhere.

Kind regards
Tony
 

mjheathcote

Centenary Club
Messages
6,406
Nice find, glad it has worked out.
Report back regarding the boot floor, I suspect that a hump is still needed unfortunately.
I must get around to inflating mine however, to check it has not deteriorated.
:)
 

Masera

Junior Member
Messages
75
Very nice!

I had my adapter made by a company here in the US, they too only sold them in pairs. Interestingly enough, I posted my spare adapter on ML forum, but it seems nobody is interested in it.
 

tonycharente

Junior Member
Messages
34
Nice find, glad it has worked out.
Report back regarding the boot floor, I suspect that a hump is still needed unfortunately.
I must get around to inflating mine however, to check it has not deteriorated.
:)
Good news / Bad news...

The good news first. Once my spare shrunk back down again it still slid into place very easily. And whilst it still does stick up above the level of the standard boot floor it does so by a fair bit less than the OEM size wheel. So yes a "hump" is still needed but it need not start so far towards the front of the car nor be so high. I've started to produce one, as I already have all I need to do so (hardboard, grey carpet and time). I'm attaching three photos - two "work in progress" of my cardboard template, and one of the wheel in place with the jack, the OEM tool-kit plus books bag and an aftermarket circular tool kit all fitting within the wheel below the level of the floor. The adapter, the five Mercedes wheel bolts, the jack handle, and expanding wheel brace and a couple of XXL rubbish bags (for a future wet and muddy flat tyre to go in) all fit in below the wheel. The five hex-bolts and all the sockets (22mm, 17mm, 13mm and a hex socket) all fit within the cover of the OEM air pump - now living to the left of the boot. My photos:MASERATI FOND DE COFFRE 1.jpgMASERATI FOND DE COFFRE 2.jpgMASERATI FOND DE COFFRE 3.jpg


And now my bad news. As stated, worried by the age of my just bought spare (2008) I inflated it to inspect the rubber, which looked fine. As a further precaution I also left it inflated for 24 hours. In that time it had dropped from 3.5 bar to 2.5 bar. I changed the tyre valve and repeated the test. Another 24 hours, and same result. I then put it back up to 3.5 bar and this time I could hear the air escaping from between the tyre and the wheel rim at one point. So as things stand other than using the spare to drive a mile or so if absolutely necessary there is no way I can rely on it.

With a normal tyre, a tyre depot would just remove the tyre, clean up (if need be) the rim, apply some magic gunge, put the tyre back on and that would normally solve it. But I'm assuming they can't do that with these tyres - which appear to only be supplied as a tyre plus rim combination?

I will take it along to a local Porsche indie who has a tyre fitting machine (I believe some Porsche also use SPACE MASTER tyres) to see if he can help me, but meanwhile any ideas please?

Also now might be a good time to check out your own SPACE MASTER !!!

Kind regards
Tony
 
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claymore

New Member
Messages
4
Lot of impressive investigation and work done here, all very useful.There may be a number of people who would prefer to have a usable spare option, rather than rely on the dubious emergency inflation kits. Would you mind summarising all the parts needed, rim, adapter, tyre, bolts etc, with full specs (manufacturer, part number, size, source, price..) to allow purchasing and assembly with the minimum hassle. Much appreciated, thanks,
Alan
 

tonycharente

Junior Member
Messages
34
Lot of impressive investigation and work done here, all very useful.There may be a number of people who would prefer to have a usable spare option, rather than rely on the dubious emergency inflation kits. Would you mind summarising all the parts needed, rim, adapter, tyre, bolts etc, with full specs (manufacturer, part number, size, source, price..) to allow purchasing and assembly with the minimum hassle. Much appreciated, thanks,
Alan
Mike's exceedingly complete and helpful very first post contains all this information for the OEM size tyre (185/60 17).

I chose to go with a narrower version (Mercedes SLK, tyre size 145/70-17). Mine was from a "W171" SLK (2004-2011, Mercedes part number 1714000202) and consequently the lug bolts (which came with it) were M12x1,5, so my adapter needed to match this obviously. With hindsight I should have bought one from a "W172" SLK, (2011-2018) part number 1724000002) as this would have been more recent - these have M14x1.5 lug bolts - same as Maserati except that these Mercedes wheels have "ball" as opposed to"cone" lug bolts.
Hope this helps.
Tony
 

tonycharente

Junior Member
Messages
34
Latest updates (in case anybody is still reading !)

My boot floor project is progressing nicely - hardboard carefully cut to shape and all fitting nicely. Next step will be to cut the carpet to match and glue it all together. I'm attaching four more "work in progress" photos.MASERATI Fond de coffre 4.jpgMASERATI Fond de coffre 5.jpgMASERATI Fond de coffre 6.jpgMASERATI Fond de coffre 7.jpg

Regarding my leaking SPACE MASTER problem, this is not yet fully resolved. My local Porsche indie unfortunately had never had to try to deal with these tyres, and he was unable to use his tyre machine to break the problem tyre to rim seal and apply tyre sealant as you would with a normal wheel. My Internet researches suggest that only Vredestein have a machine to fit these tyres. However having inflated the tyre to 3.5 bar on Thursday and its having dropped to 2.5 bar by the following day, the tyre was still showing 2.5 bar when I picked it up this morning (Monday). I had to deflate it this afternoon in order to advance my boot floor project, but having liberally applied washing-up liquid to the problem areas I've put it up to 4.0 bar and will now leave it several days to see what it drops to. The saga continues...
Tony
 

JonW

Member
Messages
1,823
I’m reading too - and am impressed by the dedication to detail.

I have just picked up a genuine Maserati spare wheel and humped floor cover, and am planning to inflate it next weekend to see if it holds pressure. How easy is it to get the tyre back down to flat after it’s been inflated?