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Winter wheels

J

JWrigglesworth

New member
Hi Everyone
I'm the proud owner of a 2003 996 turbo and I'm wanting your comments on the following.
Present wheels and tyres are
front - 235/40R18 - overall diameter 645mm
rears - 295/30R18 - overall diameter 634mm

I'm looking to fit winter tyres and rims from a 997 C4 with the following specs
front - 235/35r19 - overall diameter 647mm
rears - 295/30r19 - overall diameter 660mm

the fronts are virtually identical, but will the difference in diameter on the rears cause me a problem?

James
 
Welcome James!

I don't think the diameter difference will make too much difference. I have a similar difference on the rears on my Cayman winter wheels/tyres, and it isn't an issue. Most important is to check the offsets are compatible, not just the widths.

On the other hand, I personally wouldn't fit 19" wheels on a 996. They were never designed for them. Cosmetically the right style can enhance the look, but the ride quality will suffer.
 
Having "cured" the occurances of PASM activation simply by replacing the worn front tyres, moving up from 634 O.D to 660 O.D. would in my opinion upset the system in a similar way and the last thing you need in the winter is random application of the opposing brake. When it happens unnecessarily the effect is quite strong as the car is attempting to correct an instability that isn't there. That said by poking about in the obc maintenance menu I did find an option marked tyre change or something, but if you recalibrate for 660's you will then have to do it again when you change back. What think you Richard?
 
Hi James

I have a 52 plate 996 turbo where a previous owner has installed 997 19" wheels

The diameter of the wheel is OK but there is a potential issue with the width of the tyre (mine are 305/30 R19) touching the outer wheel arch when cornering or driving through hollows when the suspension is depressed as there ain't a lot of space left in the wheel arch

Suggest measure up 10 times and buy once!

Adrian
 
Nice one Ady
The only issue is Ebay finger strikes again, so Bought once is at the fore.....

The offset is 5mm greater so they should fit under the arches okay.

Only time will tell, I'm fitting them tomorrow.
I'll post some before and after photos.
James
 

ORIGINAL: 924nutter

Having "cured" the occurances of PASM activation simply by replacing the worn front tyres, moving up from 634 O.D to 660 O.D. would in my opinion upset the system in a similar way and the last thing you need in the winter is random application of the opposing brake. When it happens unnecessarily the effect is quite strong as the car is attempting to correct an instability that isn't there. That said by poking about in the obc maintenance menu I did find an option marked tyre change or something, but if you recalibrate for 660's you will then have to do it again when you change back. What think you Richard?
Click to expand...
There is 26mm difference on these two sizes. On mine I have 25mm difference between my summer and winter rear tyres, and the PSM doesn't seem at all fussed by it.

BTW - PSM is Porsche Stability Management, and PASM is Porsche Active Suspension Management. Two very different things, but I understood what you meant. I don't think there is an option for tyre changing in the OBC, but I believe there is one in the PCM settings.
 
Hi All
Well the wheels looked quite nice but not just right.
Also, I'm learning that there aren't any tolerances built into 996 turbos, the rear wheels catch on the wheel arch inserts
so if anyone is interested in buying some winter tyres & alloys originally from a 997 C4s they're here.
James
 

ORIGINAL: JWrigglesworth

Hi Everyone
I'm the proud owner of a 2003 996 turbo and I'm wanting your comments on the following.
Present wheels and tyres are
front - 235/40R18 - overall diameter 645mm

James
Click to expand...
I thought the front wheels on 996 turbos are 225/40R18?
 
so did I, but that is what Carlton garage fit on mine.

ORIGINAL: minny


ORIGINAL: JWrigglesworth

Hi Everyone
I'm the proud owner of a 2003 996 turbo and I'm wanting your comments on the following.
Present wheels and tyres are
front - 235/40R18 - overall diameter 645mm

James
Click to expand...
I thought the front wheels on 996 turbos are 225/40R18?
Click to expand...
 
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