Spare Wheel Installation

[berty987]

The part number for the 987C / Boxster is indeed a 996 part , I think its for cars with PCCB , but probably more to do with the wider tyres on the turbo and 4S making the rolling radius bigger and the need to keep the cross axle wheel speeds the same to ensure diff wear isn't an issue. Its certainly not the same wheel for the standard 996 / S . I've owned both the original 997/987 space saver and the 986 item , I eventually sold the 987 / 997 one because it was just too heavy and cumbersome to carry about. After damaging an alloy and tyre I was grateful for having the 986 space saver to get me home , so I have real world experience of when and where this device comes into its own. If the 16" space saver with collapsable tyre fits , thats great news, but Id still check carefully what tyre inflation pressure it needs to be pumped up to , and the limits of the OEM 987 tyre inflator. Porsche list a different tyre inflator specific for the collapsable spare on the 996 turbo. Personally I prefer the pre inflated 17" tyre as it saves time and hassle at the side of the road.

 

[Motorhead]

Mike/Richard, Very interesting posts but with all these numbers (wheel diameters, aspect ratios, rolling radii, etc.) flying around, I'm getting a little bit confused. And then there's still the issue of whether or not the damaged wheel will fit into the car after removal? My Cayman's running on 19" wheels and has an LSD. Which space saver wheel would you recommend for this set-up? Jeff

 

[Richard_Hamilton]

Mike has got me worried now, so I'm going to check it out on the car tomorrow, and I'll post some photos.

 

[Richard_Hamilton]

Panic over! It fits absolutely fine. Here is the 16” spare wheel fitted (but not inflated):

Caliper Clearance, about 8-10mm all round:

Front wheel on engine cover. This is a 19” wheel.

About 1.5” clearance:

Seats right back:

I reckon a rear wheel will also fit, as it is 1.5” wider, and if necessary I could put the seats a bit further forward as way of getting more space if I had to. As far as overall diameters go: 235/35/19 – 647mm 265/35/19 – 668mm 165/70/16 – 637mm (996C4 collapsible spare) – 36psi 105/95/17 – 631mm (986/996C2 inflated spare) – 60psi 185/60/17 – 658mm (996C4S/996T/9x7 collapsible spare) – 41psi Therefore, the 185/60/17 spare would be a better match, as it falls between the front and rear sizes. However, it doesn’t bother me too much having the 16" wheel, as I don’t have a LSD fitted, and I figure that I can put up with switching off the PSM in the event that I have to use it.

 

[Motorhead]

Many thanks for that piece of investigation Richard. The 19" rear wheel certainly would be a snug fit if placed on the engine cover. Although I've not tried, I suspect that it would fit in the front boot without fouling the lid if it were canted back towards the fuel tank, although the luggage would require rearranging. One of the advantages of the Cayman over the Boxster in this respect. Looks as though I'll need to go down the 185/60/17 spare wheel route if I choose to pursue this further and second hand wheels are likely to be rare. I'm just wondering how much of an issue the fact that I have an LSD would be given that you're restricted to 80kph with the spare and that this would equate to a relatively light throttle (I believe that the diff has a locking factor of 24% under load and 27% on the overrun - not particularly aggressive). Thanks again for your input. Jeff

 

[berty987]

Good work Richard, I'm pleased both the 16 and 17 inch wheels fit, it allows more options for those looking to buy a used space saver for their cayman or boXster. The lower tyre inflation pressure to the pre inflated version should also hopefully mean the original type pump will cope with inflating it , just remember it can only be plugged into the cigarette lighter socket as all the other 12v sockets in the car have smaller fuses and cannot cope with the power draw.

 

[Buddy]

Well Richard you've certainly put in a lot of effort on this and it does look worthwhile, before seeing your photos I wouldn't have credited that a rear tyre could fit as you've shown but it demonstrates that it is possible to carry one and in a place not normally occupied with luggage after all we have two boots.

 

[NNH]

Nice work Richard! I have a 986 spare living permanently on my engine cover, next to a Halfords jack. I got it last year to drive to Romania and back, as I wasn't convinced I'd be able to get a Porsche tyre repaired/replaced in emergency.

 

[berty987]

It may be useful to those considering buying a space saver to know the part numbers for the two options. I will find the details for the 17" , can you get those for the 16" Richard ?

 

[Richard_Hamilton]

ORIGINAL: berty987 It may be useful to those considering buying a space saver to know the part numbers for the two options. I will find the details for the 17" , can you get those for the 16" Richard ?

Unfortunately, mine doesn't have the part number sticker like yours. From what I can make out on the parts lists the numbers for the 16" wheel should be 996.362.050.00 (replaced by 996.362.050.01). This wheel is shown for all 996 C4 models, and 996 C4s and Turbo models up to MY2003. I think this was when they introduced optional PCCBs. The number quoted for later models is 996.362.020.01 (superceded by .02/.03/.04) which I presume to be a 17" wheel. Maybe you can confirm that. I can't seem to find the 996.362.120.03 number shown on your sticker on the system.

 

[sulzeruk]

An alloy jack from a 944 will fit the jacking point on the underside nicely, tried it on my 996 today. It may be possible that the collapsible 944 wheel may fit the car as well. Alasdair