Vibration almost like a tire out of balance

[georgec986]

My '97 has an issue when I first begin driving it, goes away after a little while - car shutters as though a tire is out of balance. But after driving several miles, it's either completely gone or is subtle enough that it's hard to notice (or at least hard to notice by comparison).

To make it more annoying, how long the car has been sitting does not seem to add to the problem - I've parked it for a few hours on a relatively warm day only to have it happen right away. But it does seem that the colder the weather, the stronger the vibration.

A couple of years ago I upgraded to larger (and heavier) 18" wheels - the problem is more noticeable with the 18s vs the OEM 16s

Car tracks pretty straight, wanders a little but highways here in CT aren't the smoothest. Suspension is stock except for a larger front swaybar and the 18" aftermarket wheels.

It sits in the garage most of the year, so it's one of those things you don't think about until I finally take it out. I hadn't driven it in well over a month and finally took it out last week, outside temperature was somewhere in the 20s, vibration was very obvious.

thanks

[Beelzy]

It is the tires. They are too hard due to the colder weather and they are not tracking correctly

I noticed the same issue when the temp drops. It is advised to use winter tires when the temp falls

below 45 degrees. Especially if ice or snow is a concern, you can slide right off the road!

[motobob]

Agree, flat spot and after the tire gets warmed up; the vibration goes away. Also check your tire pressure! Bob

2001 Boxster S

[juniinc]

classic tire flat spot symptom,,, when I had my Kumho they used to vibrate horribly for roughly 20 minutes.

We've been getting mass snow in seattle I just move my car back and forth frequently,,,

[georgec986]

classic tire flat spot symptom,,, when I had my Kumho they used to vibrate horribly for roughly 20 minutes.

We've been getting mass snow in seattle I just move my car back and forth frequently,,,

Thanks everyone, that's what I hoped for (since it's the cheapest...)

And like Juniinc, I'm running Kumhos which could be the culprit. The original Pole Positions had a tiny shake but then again, the car does sit a while so the flat spots aren't surprising.