Landseer

Have one car with 18s.
Drove it to NJ and back a few weeks ago.
Bent a rim on a moderate pothole during the trip.

Its going back to 16s to improve ride quality.

BReyes

So we can spend more ... same as everything. You know answers to your q's. I like the 997 wheels too.

p.s. was reading the Cayenne forum's sticky on service/warranty issues so I missed today's practice. Often its this one. .

Regards,

mallman

what size rims do they run on nascar, when brother started putting large rims on ,little brother wanted to be like big brother.

dcrasta

I was under the impression that for Race cars, larger wheel / smaller sidewall combo :Benefits -

-Less unsprung weight (light weight materials used for wheels can reduce the weight on the suspension)
-Larger footprint (larger diameter tire of the same width will have a longer tire patch.)
-Less sidewall deflection (more steering input and feedback)

The disadvantages.
-Less air volume (tire temps can increase)
-Less 'sidewall' to provide compliance. (rougher ride)
-More expensive/harder to mount (small sidewalls are more difficult because they are less compliant).

Everything is a trade off. I think the 928 suspension springs are engineered for the tire/wheel combo . If you are going to go with smaller sidewalls, you may need less spring rate or a progressive spring.

I like the look, but my car is a street / Daily driver and NE roads are too unforgiving for /35-40 series tires.

S4ordie

JWise and I both run 17" Front and 18" Rear Cup II's. I have Bilsteins with stock springs/coils. The ride is very good. The 17" wheels up front mean taller more compliant tire height which equals a less harsh ride. The car handles very well and I recommend this set up when you can find the 18" rear wheels (Mille Migilia).

Randy V

You ask why, I ask why not.

hacker-pschorr

RKD in OKC

Googled up a Car and Driver test done with plus sizing wheel tire combinations on a VW golf.
Plus sizing is where the overall diameter of the tire is the same regardless of the rim diameter.
They did 15, 16, 17, 18, 19.

In ALL cases...The larger diameter the rim, the Heavier the wheel tire combo.

Only the 17 and 18 had the same width rim and tires as each other. 18 was still heavier than 17. Generally the larger the rim diameter, the wider the rim and tire section.

Performance...
Larger rims were heavier, slower in acceleration, got worse gas mileage, and longer braking 60-0 except 18 and 19 were same.

Larger rims and wider tires cornered at higher G except the 19 was a bit less than 18 even though the tires were wider section. Both 17 and 18 had same section width but 18 got higher cornering G. Article stated that available 18, 19 tires were stickier and had a higher speed rating than what was available for 17, 16, 15.

dr bob

Malcolm--

I have 17" wheels with PS-2's, great compliant ride at 90k with stock springs and original shocks. Over time maybe the ride was a bit 'too' compliant. The opportunities came up for OEM replacement shocks and Eibach progressive-rate springs, so I grabbed both. On installation, I was impressed by the improvement in handling feel (less body roll) but the ride quality suffered. From previous discussions here you might remember that I was seriously considering going back to stock springs on the new shocks. It's several thousand miles later now, the shocks have gotten past their initial high-friction period, and the car is a lot less like an ice wagon. Ride has improved a lot with less teeth-rattling on small road irregularities. It's most apparent with the reduction in odd vibration noises that had appeared with the new springs and shocks.

The Eibach springs are a good handling vs comfort compromise for me it turns out, but my lasting concerns are around the inability to get the front up to spec ride height. I have it at about the highest possible setting on the front adjusters with threads still engaged, and it sits at 173mm. That's barely north of the 170mm minimum allowable with worn/sagged springs and tired shocks, and a bit south of my target 180mm midrange in the factory height range. If my springs or shocks sag or wear much, I won't hae any recovery room. Plus where I live I need the little extra height just to get the car in and out of the driveway straight on; as it is I just need to choose the attack angle and location a little more carefully. I need a simple 15-20mm ring spacer for the front adjusters to get the adjustment range to match the factory ride height range. The rear heights are OK so far, but the adjusters are maybe 2" off the bottom of the threads, ride height matches front at 173mm with a full tank but no other load. I don't know what your ride height targets are, or how your road conditions compare with those in SoCal. We don't have frost heaving, but we do get the occasional pothole. These aren't like real potholes though, more like just a patch where the top layer of asphalt has departed. Maybe a 2" depression.

hacker-pschorr

I have two sets of replica Porsche 17" wheels that are heavier than my 18" Carrera III's with tires.

Most of the aftermarket replica wheels feel like they are cast from solid lead.

the flyin' scotsman

Interesting comments, well except for Randys

The suspension discussion brings me back to thinking it would be nice to compare a new set of OEM springs with the Bilstiens to the Bilstien/Eibach set up I have now. I've discussed this before I would have made the change before if it wasn't for the work then required alignment.

As the wheels will be soon fitted I'll make that comparison then make the suspension decision.

The car does have a very modern look with updated rims.

hacker-pschorr

You just answered your initial question

Sorry, all the 928 wheels' between the phone dials and GTS cup 1's look like they belong on a Buick, not a Porsche.

Even fuchs in a 928 offset would be nice compared to the manhole covers.