Shmurzik

Well, actually, I am curious about my new wheels.

I bought them recently (thanks, Scott!), and other than a bunch of scuff marks they seem pretty good. So, I washed them, etc. then put them on the balancing machine and noticed that at least one of them was... how should I put it... somewhat wobbly. What I couldn't quite see was the reason - was it the rim itself or the tire having settled in a crooked way.

Is there any way to tell without unmounting the tire? I put the wheels on tonight, so far so good - there is some vibration, but this is Northen California, so the road are crap + the tires maybe a little harsher (they Dunlops SP9000 vs. Kumhos 712 on the old wheels). I have used them on a highway yet. Thank you, all.

saxapeeel

id ont know anything about your tires, but i can fully agree on your northern california roads comment. try living in petaluma and cruising those roads! ...unless you do live here.

ErnestSw

Remount the wobbly wheel on the balancer and spin it. Place a screwdriver on a horizontal surface so that it's just touching the wheel rim. If the "runout" is in the rim you'll get intermittant contact. If it's in the tire the contact will be steady

Lizard928

dont mount the wheels before you find the problem, unless you want to cook or cause unessacary stress on the suspension componants

Shmurzik

great idea!

Another moment to consider is that the rim are an inch bigger, hence the ride should be a little harsher. Took on the highway this morning - seemed okay, but I only get a relatively smooth stretch of 280 going south , so we'll see what happens tonight.

Jim bailey - 928 International

Porsche allows for up to 1 mm of maximum radial or lateral run out . This is best checked with a dial indicator and the wheel mounted to a spindle . Or as mentioned a visual check will indicate if the rim is bent . And 1 mm is not very much ! Many people are driving around on rims bent far more than that and do not know it .....

Shmurzik

Jim,

Are you saying that I shouldn't worry about this unless the car starts behaving weirdly? Thank you.

Jessa

See the write-up in the IJ lately? Its offical now. Petaluma got voted Worst Roads in the Bay Area, with Marin coming in second!

Jim bailey - 928 International

Not knowing how much of a wobble bend you have it is hard to say what it will feel like at various speeds . But usually a "small " amout of out of round has little efffect since the tires are not round true either . I would expect that the rims drove fine for Dr Scott should be fine for you as well .

Shmurzik

But what if mine is more discriminating taste in wheel circumference substantiation?
I am, after all, quite a connoisseur of all things round



Thank you all for your answers!

Tahoe Shark

If you think the Bay area has bad roadways, come up to Tahoe. Potholes that swallow 4x4's, chain marks that rattle your teeth and don't forget about the SAND on the roads. I thinking about putting a lift kit and 12.5 / 16.5 studded snow on the GTS for winter.

Jim bailey - 928 International

Tim bad visual ... your GTS should be safely sleeping in a heated garage ............. . Preferably your own !

Lizard928

you can put it in mine if you dont have 1

Nicole

Is it a front or rear wheel? I don't know at what speed a front wheel vibration would show in the steering of a 928, but if there is a problem with the rear wheel, you'd feel a vibration of the whole body at speeds of approximately 80 mph.

My car does that after the long stretches of sitting in my garage. It often sits for two or three weeks before I take it out again, and the first miles I get a free massage. Apparently, this evens out as the tires warm up.

I used to own a Renault Fuego in Germany, which had four beautiful aluminum rims with the roundness of eggs. When I got new tires, I had to take the car to a special shop with a grinder that - after mounting them on the rims - grinded the tires to make the whole thing round. Then they were put on the car, the valve position was marked, and the whole thing was balanced on the car - the only way to keep this thing from vibrating...

Joe '87 S4

The chain marks were terrible on a trip to Reno last year. But, at least they were consistent. In general the Bay Area has to have the worst roads in the nation.
It's pretty bad when you swerve back and forth in a lane because you know where all the potholes are and if you watch in your rearview mirror, the cars behind you are following your lead.