shortslr

I actually found a little open real estate on the Merritt Parkway in Connecticut. I decided to stretch my legs a little. When I got to 100 though my front end started to shake and I had a vibration fairly severe in my steering wheel. It sounded like a golf ball stuck in the tire. My last service was about 10k miles ago when I had the tires rotated last and a front end alignment. I did however have a flat a month or so ago which I had patched instead of replaced since my tires are fairly new. So I am thinking when I went to the tire shop for the patch and they put the weights on the wheel to balance it wasn't calibrated precisely enough for that speed. Tires are ok, front end doesn't feel out of alignment. It sounds expensive just thinking about it. I am going to have my tires rotated again and see if it helps. Thoughts? Prayers?

Chris W. - '96 Targa

Silly as it may sound, first check your tires' air pressures. Make sure they're the same side to side. (Yes, it actually can make a difference.)

From there, a rebalance of the tires would be a good next step, if it's not cleared up. 10k miles is a long time to go for a rebalance (haven't your rear tires worn out yet? <img src="graemlins/burnout.gif" border="0" alt="[burnout]" /> )



-Chris

sy308

A true harmonic related to a tire imbalance condition might also manifest itself with wheel vibration at other speeds. Observe very carefully at around 50 mph in similar road surfaces and see if something is also present. I would look for a weight that fell off and do a rebalance. Then you can more safely address the issue with a 50 mph speed, rather than 100! Good luck.

tom_993

[quote]Originally posted by shortslr:
<strong>... My last service was about 10k miles ago when I had the tires rotated last and a front end alignment.

...

I am going to have my tires rotated again and see if it helps.</strong><hr></blockquote>

Rotated? You mean left to right? I’m not sure that’s recommended for “directional” tires, which our high performance tires often are. What kind of tires do you have? I agree with the comments above: check the balance, pressure and lug nuts.

Tom
’95 993

Here’s some info about rotation from the Tire Rack:

<a href="http://www.tirerack.com/tires/tiretech/general/rotate.htm" target="_blank">Tire Rotation</a>

They also have a "Vibration Diagnosis Flow Chart," which I have not downloaded, but you may be interested:

<a href="http://www.tirerack.com/tires/tiretech/general/vibechart.htm" target="_blank">Vibration Diagnosis Flow Chart</a>

shortslr

Thanks everyone for the kind suggestions. I have Pirelli's on and when the tires were last rotated, I believe he swapped front and back, not across. He races so I would he did the right think it occur to me call and ask at this pt. I checked the tire pressure all around. I was 34 on two 33 on one and 36 on the other. They are all at 36 and haven't had open highway to get to 100. 50 there's no vibration, 80 a little, 100 and feel like you're in a Toyota. It's gotta be the weights. I checked treads on the tires they more than 1/8, more like a quarter deep, those on the outside, especially in the back they look like they are balding.

tom_993

[quote]Originally posted by shortslr:
<strong>Thanks everyone for the kind suggestions. I have Pirelli's on and when the tires were last rotated, I believe he swapped front and back, not across. He races so I would he did the right think it occur to me call and ask at this pt. I checked the tire pressure all around. I was 34 on two 33 on one and 36 on the other. They are all at 36 and haven't had open highway to get to 100. 50 there's no vibration, 80 a little, 100 and feel like you're in a Toyota. It's gotta be the weights. I checked treads on the tires they more than 1/8, more like a quarter deep, those on the outside, especially in the back they look like they are balding.</strong><hr></blockquote>

Rotated front to back? Sorry, but I don’t think so. The rear tires are substantially larger than the fronts. I’m not sure they would even fit in the front wheel wells. If they did, well I can’t even imagine how weird it would look.

Some Pirelli’s are directional and some aren’t. If they are the non-directional type, swapping side to side is OK (The old rule of thumb was to never reverse the direction of a radial tire. I think that old rule is out of date now). If they are directional, swapping left to right will make each tire turn in the wrong direction. One of the major reasons not to do this is water removal when it’s wet. The grooves are meant to evacuate water in while turning one direction only.

Sounds like you are pretty close to needing new tires. Depending on your budget, uses for the car, etc, you might want to save the cost of having these old tires balanced and get a new set. If you have the old ones balanced now, you’ll just have to spend that money again when you get your new set mounted and balanced.

Tom
’95 993

shortslr

yes it turned out to be the tires. I had a few choices as to which tires to get and wasn't sure so I did a little surfing on the web. I went with the Bridgestone tires, though Dunlop came in a close second with surprisingly Pirelli's coming in worst of all the reviews. My mechanic said he disliked the Pirelli's