I need a Spare

bremen · 10-05-2008, 08:34 AM

I don't have a spare and the last two I tried would not fit. I have measured the backspace on the 15" Fuchs on the car now by turning the tire over and holding a T Square from one side of the rim to the other, then by taking the measurement to the lug hole I get 103mm
When I do the identical measurement on the rim I bought as a spare, that measurement comes to 126mm, plenty of room to spare I thought. Not so when putting the spare on the car it cinches onto the calipers even with a 1/4inch spacer on the car. WHERE AM I going wrong?? Thanks for your time. Karl

racer · 10-06-2008, 01:32 PM

A picture is worth a thousand words!

First off.. 4 bolt or 5 bolt?

What size/type brakes?

bremen · 10-06-2008, 04:22 PM

The wheels on my car now are Fuchs 15inch x7 in the front and 8 in the back. There is a 1/4 spacer on the front to clear the calipers now, and the 930 brake calipers on the front have been shaved to get the tires on the car.

racer · 10-06-2008, 06:22 PM

Why not just get another 7x15 fuch/cookie cutter for use as a spare? What kind of "spare" are you referring to in the first post?

bremen · 10-06-2008, 10:42 PM

Racer I may have to do just that. I was hoping for a smaller liter tire since the oil cooler in the front trunk takes up room to only use a mini spare, but not much more. The 944 spare is such a tire, weighs a ton, but would fit into the space designed for the spare.

carr914 · 10-07-2008, 09:48 AM

Karl, you have posted this question on at least 3 forums. On the World, I asked you about what brakes you had and you never answered. It boggles my mind when people ask for help and then don't respond to offers of help.

Anyway my suggestion would be to get a 7x15 cookie cutter and have a mini inflatable spare tire mounted

bremen · 10-07-2008, 11:52 PM

I did answer the question what kind of brakes I have by stating that I had 930 turbo brakes on the front, my rears are vented Carrera brakes and rotors, that I did not mention since I though if they fit in the front they will fit in the rear.

The problems with just going an buying another wheel and having a tire mounted is fine but knowing what and how I need to measure the backspace is even better since wheels will be different and once I buy it and get it home and it does not fit, what do I do go and grind more off the calipers to make it fit? I don't mean to drive you or anyone else nuts, but after trying two spares already and having to drive a couple of hundred miles to return one of them I would like to be reasonably certain the next one will fit.

racer · 10-08-2008, 12:56 PM

I know what you mean about using up some space re: the oil cooler as I have the same issue. For my though, I turn the same size spare upside down and put things like a qt of oil, brake fluid and some shop rags in it.. then throw my tools and other stuff around it. I leave the carpeted panel at home. That said, for my application, the factory 165-15 on stock rim DOES fit with a modified carpeted panel.

The issues with the spares, likely has more to do with the rims design/shape than offset or backspace.

IIRC, the minispare rims, on the backside, are not smooth where the vertical face meets the horizontal area (where the tire mounts). So, you likely would need at least a bigger spacer (to help get that area away from the caliper) or look for a 16 or 17" spare from say, a Boxster.

Oddly enough.. in 30+K miles of porsche driving (mostly on weekends, DEs and AXs), I've never needed a spare.. Knock on wood.

bremen · 10-09-2008, 03:10 PM

Mikez sent me a link that tells the offsets on factory Porsche wheels, I'm including it here for those that may have a need for it.
My question is this, since both backspaces for front and back wheels is 112mm but the offset is different, the front is 23.3mm and the rears are 10.6mm will the spare that fits on the front, fit on the rear?? Thanks Karl

http://members.rennlist.org/911pcars/WheelWts.html