997 wheel fitment question
09-17-2009, 09:13 PM
#1
Instructor
Thread Starter
997 wheel fitment question
[I posted this in the wheels/tires forum but there seems to be little activity there. Pictures of the wheels in question are with that post]
I'm trying to put together a 2nd set of wheels/tires for my 05 C2S cab, for track use. I have a set of lobster fork wheels (19-in) ready for tires. I found 4 slightly used Dunlop sp sport 9000 tires - see pics - on polished Imola wheels, which I care less about (though they are nice looking). They came from a 2002 911 Turbo.
Here's the question: The rear tire size on the Dunlops is only slightly off from my stock size: 275/30 ZR-19 vs. 295/30 on my car (the fronts are identical). I spoke to my dealer service manager and he said the tires should mount on my OEM lobster forks fine, but because of the narrower width on the rears "there may be PSM issues, including it might not function." If so, that's bad news for the track and a deal-breaker for me.
The price and condition and even the convenient location of this set are ideal, BUT -- will they actually serve the purpose safely? All input welcome.
Gene
I'm trying to put together a 2nd set of wheels/tires for my 05 C2S cab, for track use. I have a set of lobster fork wheels (19-in) ready for tires. I found 4 slightly used Dunlop sp sport 9000 tires - see pics - on polished Imola wheels, which I care less about (though they are nice looking). They came from a 2002 911 Turbo.
Here's the question: The rear tire size on the Dunlops is only slightly off from my stock size: 275/30 ZR-19 vs. 295/30 on my car (the fronts are identical). I spoke to my dealer service manager and he said the tires should mount on my OEM lobster forks fine, but because of the narrower width on the rears "there may be PSM issues, including it might not function." If so, that's bad news for the track and a deal-breaker for me.
The price and condition and even the convenient location of this set are ideal, BUT -- will they actually serve the purpose safely? All input welcome.
Gene
09-17-2009, 11:04 PM
#2
Poseur
Rennlist Member
Rennlist Member
There is usually a range of tire sizes published for each rim size (width). Just off the top of my head I would think that a 275 should fit on an 11 inch rear rim.
As you state that you have a C2S and not a 4WD car then I would think you should not get negative feedback from the PSM. It's not THAT particular. It IS when you're dealing with a 4WD car, when you have a mix of tires front and rear.
As you state that you have a C2S and not a 4WD car then I would think you should not get negative feedback from the PSM. It's not THAT particular. It IS when you're dealing with a 4WD car, when you have a mix of tires front and rear.
09-17-2009, 11:22 PM
#3
Race Director
For track use you really should not undersize your tires. I use 18" CCW wheels and 245-40-18 front tires and 305-35-18 rear tires as these spec out the same diameter as stock 19" but are a little wider for better grip at the track.
09-21-2009, 04:23 PM
#5
Instructor
Thread Starter
The weird thing about the tires that are for sale (the 275/30-19 rears, that is) is that I talked to two dealers who both say they've never seen that size on a Turbo, which is what they came off of. That's a non-stock size for that car, no record of it ever being specc'ed by Porsche. For wide bodies I was told only 295 or 305 widths are used. So I don't know - I guess I'll pass. Too bad, it was a great deal.
Gene
Gene
