Wheel size limitation on 1997?

[KenJ]

Spent too much time trying to search and find.....

1) what is it that limits the size of wheels the '97s are supposed to use?

2) Is there a reference to a TSB or article that's shows what's needed to "upgrade" and use 18" or 19" wheels?

thanks

kj

[geoff]

See Mike Focke's excellent reference at http://sites.google....yeardifferences I always thought it had something to do with the wheel carrier assembly

[1schoir]

Spent too much time trying to search and find.....

1) what is it that limits the size of wheels the '97s are supposed to use?

2) Is there a reference to a TSB or article that's shows what's needed to "upgrade" and use 18" or 19" wheels?

thanks

kj

kj:

1) 17"

2) The following information obtained from Mike Focke when I asked the same questions: "from the 1998 list of changes: 18” wheel option with rear chassis reinforced to accept new wheels. Rear body structural change included redesigned wheel wells and coil spring mounts, lower engine compartment bulkhead, rear wall crossmember and rear axle mount reinforcements."

I don't think it's practically feasible to "upgrade" the parts of the car that have been reinforced.

Regards, Maurice.

[KenJ]

Thanks guys. I'll pass that along to someone who just bought a '97 and it came with 19" wheels.

I'm no engineer, but I'm guessing it's related to the manner in which the tire/wheel combo stresses the components.... i.e. how far out from the wheel centers the forces are. Seems the SpecBoxster guys are pushing the envelope with 17" and sticky rubber - but no one has seemed to have had any trouble with it.

thanks,

kj

[mikefocke]

The story I heard was that the problem of overstressing the original suspension mounts was found at the racetrack when Porsche was testing bigger wheels and stickier tires. Some use bigger wheels on '97 street cars, your risk. I wouldn't use 19"s but not for that reason. They look a bit to "poser" to me.

Do price the bigger diameter tires versus smaller diameter ones and look at the potential for expensive wheel damage as the height of the rubber decreases.