Tire Flatspotting
 

I know what flatspotting is -- typical case of a car sitting for awhile, you get a bad shimmy-like feel, and then after driving a while it goes away as centrifugal force takes over and rounds out the tire.

My question is: can a tire flat spot in as little as 12 or 24 hours?

And a second question: does the age of the tire affect its tendency to flatspot and/or recover from a flatspot?

More facts: the Boxster S I just bought sat around for about 18 months before I bought it. Was only driven about 500 miles. Seemed like it took 100 miles of driving to get rid of the flatspot. But now, I find that even when the car sits for 12 or 24 or 48 hours, there is a classic vibration that happens at speeds in the 30's or 40's and goes away after 5 or 10 miles of driving. I never thought a flatspot could happen that quickly, but it exhibits the classic symptoms of a flatspot. Is that possible? The tires have excellent tread, but are almost 8 years old, no dry rot. Does the age of the tires allow it to flatspot quickly?

Any thoughts?

What tire are they?

Michelin Pilot Sport A/S

This was covered about 3 months ago on this forum. They wont flat spot.

If you want to test, let it sit for 48 hours, jack up the car and turn the wheel by hand. If it was flat spotted, you will be able to see it if it is there.

Tires being 8 years old most pro's would say time to replace , regardless of miles or how good the tread looks . I think most would say 5 years is the max then replace .

Yes, I've heard "experts" say anywhere between 6 to 10 years is the useful life of a tire. But is that in any way related to the flatspotting?

So why is it showing the classic, textbook signs of a flatspot?

And btw, I did a search and didn't see anything from 3 months ago on this topic. Most recent was about 18 months ago which seemed to say that tires can flatspot overnight.

Are your tires properly inflated?

Yes. Just checked.

If your tires are 8 years old, especially being PSS, there is a good chance that you have some damage to either the internal tread or a sidewall beginning to fail. The PSS are so soft. When I had the set of PSS on my car, I noticed similar conditions, but even more concerning was a vibration at around 90-100mph. After checking the date of the tire and found them to be 8 years old I swapped them out and no more issues.

Thank you. That's very helpful.

FWIW they're the A/S tires not the Max Perf Summer, and not as soft as the Summer tires. There is no visible dry rot or other damage, but I hear you on the possible internal damage.

Did you get a vibration at speeds below 90 - 100? Besides the initial flatspot-like thumping at low speeds, I get a shimmy at different speeds between 55 - 90 (haven't gone over 90 yet)

What?
Of course low profile tires will "flat spot".
There's no way you'd see it on a pressurized tire (unless you have bionic laser eyes), but you can sure as heck feel it.

But will they do it in 12 hours or overnight?

There is not literature on tire flat spots that notes flat tires occur overnite. All assertions of flat spotting is based on long-term parked/storage.

I don’t recall offhand if the Pilot A/S 3s I had did that or not. It’s been quite a few years. Want to say yes, but I’m not sure.

https://www.michelinman.com/US/en/help/do-I-need-new-tires.html

"After five years or more in use, your tires should be thoroughly inspected at least once per year by a professional."

temperature. cold in ny, yes? even if inside, unheated concrete slab will get cold.

I am a tire expert & I say there are many variables but no way should you drive on tires that are older than 6 years. :eek:

I had very similar experience with my 4 yr old Pilot Sport A/S-3's on my 911SC. With no power steering, I feel everything from the front wheels in the steering wheel.

It seemed that I couldn't get them balanced correctly (despite trying twice) which would result in a shaking steering wheel. Sometimes it was better than other times, but it was always there to some extent.

I replaced the front tires and now it drives like a dream again.

I would recommend new tires - at 8 yrs old they are due anyway.

Here is a link

http://986forum.com/forums/boxster-general-discussions/74205-winter-storage-tips.html

Hopefully it will work. If not look for Winter Storage tips.