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View Full Version : The tire issue again, this time a little different



davis449
10-27-2005, 03:10 PM
Here's a copy of a post I put in the MBWorld Tire and Wheel forum and got no response too. Maybe you guys can help me out.

I've been hunting down a vibration problem for about three months now. A little background info.:

Bought my Kumho Ecsta ASX 215/55/16-W speed rated tires in July (my sister's boyfriend, now my new brother-in-law, took it to Discount to get them put on in Chicago). I drove it out of the city and they were severely out of balance, alignment was done right after the new tires were put on (assumed that was not going to be a problem), had them balanced in Springfield, Il on my way back to San Antonio and that made them a lot better, but I still had a little vibration. Proceeded to take it in three more times to Discount for spin balancing and each time at least one of the tires was out of balance. By this time the steady vibration had stopped and it would just do it after the car had been sitting for a while and 5-10 min. of driving would make it pretty much go away. The fourth time I had them spin balanced, I ended up taking it to the dealer and they did alignment again cause Firestone sucks and didn't do it properly (I saw the spec sheet and the alignment was way out of spec). Still had a little vibration after they did alignment and they (the dealer) told me the tires needed to be road force balanced and wanted $110 to do it. I said to hell with them and took it over to Discount and paid them $50 to do it. It seemed ok as I drove it home and the next morning when I drove it to work it still did it. Now let me describe what the vibration is. It will onlly do it when the car has been sitting for more than an hour. After you drive it for about 5 minutes, the vibration will go away and it seems fine. The best example I can give is when I left it for four days (gone to my sister's wedding) and came back. Took it out the night I got back and it was especially bad, but once again, it stopped after about 10 min. It seems the faster you go, the less you feel it. Between 60-75 mph is where you will mainly feel it, but like I said it goes away after about 5 min. of driving.

Now to my question. I took it to the dealer the next day (Monday) to ask them what the hell was going on and why, after spin balancing them four times and then having alignment done and a road force balance, I was still getting this problem. The tech went for a ride with me so he could feel it too and he told me that because these tires are W rated, they are soft and will develop flat spots when the car sits for a while. He told me to bump the air pressure 4 psi to curb the problem. They set them to 32 front and 36 rear (+4 psi from manufacturer reccommended tire pressure). I don't know if i can believe this because I have never once seen a Lexus IS 300 or any other sport car or sedan with Z+ rated tires have an issue like this (my brother-in-law owns an IS 300 with Z rated's, got two twin brother friends, one's got a Mustang GT and the other a Z28, they've never had an issue like this with their Z+ rated tires). What's the deal here? Is my dealer filling me full of crap? Should I take them back to Discount, describe the problem, and ask for a new set cause these are defective? Are they defective? Please help!

manny
10-27-2005, 03:59 PM
It sure sounds like the tires are flat-spotting.
Increasing the pressure may help a little.
I had the same problem with my Kumho's.
Installing Michelin Pilot Sport PS 2 solved it once & for all. ;)

SLAMMED_C
10-27-2005, 05:29 PM
It is true.. tires can "flat spot" if they sit for long periods of time. and as you have mentioned, thats what it sounds like is happening.. after having the car sit and then driving it.. as the tires heat up the flat spots go away and the vibration will go away.
but this happens after letting a car sit for weeks at a time.. usually dont a few days. may be a soft compound in the tires that causing your problem.. the only real way to get rid of it is to replace the tires with a different brand.

c55m8o
10-27-2005, 05:38 PM
Both my Goodyear Eagle F1 GSD3 tires and Bridgestone Potenza SO3 Pole Positions would flatten if sitting outside in the sun while I'm @ work ; worse then they do sitting in my garage overnight. It's a trueth that soft tires flatten while sitting.

But what you describe is more akin [basically, exactly] to what I have ... bent, non-round rims on the inside drums. Maybe silly question, but has anyone looked closely at both the outside surface of the tires & inside surface of the rims when they are spinning on the balancer? I have wheels that balance 100% perfectly; however the rims dip in from 1/8 inch to 1/4 inch in several spots on the left rim. And I was getting a terrible shake between 60mph and 70mph; practically smooth as glass below and above it.

(of course, now inner and outer drums are totally shot after a terrible encounter with a piece of missing roadway the width of the entire lane on the way into the Lincoln Tunnel, so I really have to send the rims to Kineses to get re-drummed, sooner now then later.)

I personally also think you can kick the fronts up in air pressure quite a bit. The air pressure recommended on the inside of the gas filler box is for stock tires; not the tires you have; and oriented for comfort, not performance. Before I totally killed my rims, I got rid of my shake when I ran 40+ PSI in the fronts. Basically then, the tires balloon and I'm running in the centers, away from the bends in the rims...! :eek:

benzfan
10-27-2005, 05:40 PM
The above replies are right on the money. My rear Kumho Ecstas (255-35-18) flat spot noticably. My old Dunlops were the worst, and the Pirelli P-Zero Neros on my 17" wheels are pretty good by comparison. Newer tires are not too bad compared to the late '70s radials. I remember taking a ride in a Datsun 280Z with an aftermarket turbo back in '79 or so. It had been sitting for about a month at that point. It went like stink but shook like a dog s****ing a peach pit for the first 10 minutes until the flat spots rolled out.

davis449
10-27-2005, 07:38 PM
OK so what I'm gather ing so far is that this tire flat spotting thing is pretty normal and that it's not a real big deal. The rims have been looked at they're fine, I think it's a soft compund. This is the first time I've ever had anything aobve H rated on a car, so I'm not accustomed to having a softer tire like these. Thanks for all the responses guys.