Ern

Hi all, My 928, sometimes sits for a month without being driven as I have a number of collectable cars to drive. I have a problem keeping the tires from developing flat spots. The tires are out of round by a little less than 1/16 of an inch (0.055 inch). After balancing they still are not smooth running. I may have to replace the tires(only 7,000 miles on them). The wheels are within spec. Any ideas on how to save the tires and how to prevent the problem in the future. A friend suggested parking on carpet. The tires are Goodyear Eagles GT4 P225/50/R16

Thanks, Ern

Nathan Valles

You didn't mention how old these tires are. Have you tried getting the dealer to replace them? Maybe get Goodyear to give you a new set. Call them defective.

When ever I had tires with flat spots the flats would always disappear after a few minutes to 1/2 hour of driving. Obviously this isn't your problem. All I can suggest eother drive it more often, try switching to another tire or put the car up on blocks when you aren't driving it. It'll take a few minutes but at least the tires will stay round.

DP

I had tires a few years ago that went "out of round" and I was told that if I wanted to solve the problem without replacing the tires I needed to have then shaved ...I lived in Pasadena ,Ca at the time and was told that the only place in the area was Caldwell tire in Pasadena ..You might ask around at tire stores I don't think that too many tire shops shave tires ...

Ern

Thanks for the ideas. I know I should put the car up on blocks, but then It will sit even more as I have to get it down to drive it, lazy I guess. I have called a number of tire shops and have not found one that shaves tires yet. The Goodyear tire guy said that radials shouldn't develope flat spots from sitting that won't go away after driving. He thinks I flat spotted them from braking. I did smoke them once braking but I don't think that is the problem as I have measured the tread depth and it is the same on the high spots as the low spots. My plan is to pump them up to about fifty pounds, drive them for 50 miles on a hot day, measure them. Then I will call around until I find someone that will shave the tires and then have them balanced. There must be someone in the area that shaves tires. I live in Camarillo, so Pasaedna is not that far. How about balancing them on the car vrs. off the car? Thank for the help, Ern
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John Struthers

Ern,
The Goodyear Rep. has, apparently, never been to the Mid-East. Which is supposed to be the capital of flat spotted tires.
The temperature difference between smoking roads
and relatively cool covered/sub floor parking does a number on the rubber as well as the wire cording. Eventually resulting in the noble flat spot. I might add that vehicle weight and sidewall ply play an important part in the the flat spot or the lack thereof. Additionally, I cannot recall a single case of a Taxi giving me a 'cam lobe' ride and they are constantly on the go. One of our members is based in Riddyah, Saudi Arabia. Maybe he could comment. The Goodyear folks have a closed developmental test area in Southwestern Texas, Ft. Stockton(?) I'm sure the racing department used to shave tires for the racing community as well as the Bonneville Flats crowd. Ask your rep for a phone# or surf for it.
In any case, I wish you good luck and drop us a line if you get the straight scoop from Goodyear.
John S. 82'Weissach, Auto., 'Pattycakes'

jpitman

John S, were you calling my name?
A friend here was given a low mileage Sonoma pickup at work - been rolled but fixed up fine, should be good. Mmmmmm handles VERY strangely, no wonder it rolled. After a few weeks of hair raising driving we investigated, and found all the tyres were at 50psi, AS DELIVERED from Dealer! We asked them - Oh, thats how they are shipped to prevent flat spots. We must have forgotten to deflate them on arrival. Duhhhhh. Down at recommended psi, it was a different truck.
YMMV, but its worth trying. Also, note that 4x4 shops sell tyre deflators that you set to whatever you want. You could park it up, inflate to 50psi, and when you want to drive, put a deflator on each tyre, make other preparations while they go down to pre-set pressure, and drive away?
Yes, we have very hard bitumen here, and lots of dust, all conspiring to reduce grip and promote squealing on corners.
JP Riyadh

ldrhawke

I've had the same problem of tires out of round with my 928's. Tires with nylon cords seem to be the worst. The nylon gives the tires more high speed strength, but let them sit for a few hours and they take a set. Let them sit for a month and the set may never come out.

Try dropping the pressure to 10 lbs before going to a higher pressure. Surprisingly, the car still handles reasonably well even with the pressure that low. Then run them for 10 miles on the highway. Don't try to be a hot dog on the off ramp with the low pressure. Directly afterwards, while they are still warm, put 50 lbs of pressure in them.

They will heat them up a lot more and maybe allow for the hotter tires to reshape the nylon cords when 50 lbs is put in them.