Hi all - thanks in advance for your assistance! My fiance narrowly avoided rear-ending someone on the highway (sudden traffic backup - phew!) but she ended up with a flat spot on each tire. They are noticeable at even very low speeds and at high speeds, they make you think a Harley is next to you. My first question is assuming the flat spots are not dangerously worn, would the constant vibration lead other problems? Second question is how would one determine if they are dangerously worn?
It doesn’t matter. They need to be replaced anyway. When a flat spot develops like this the tire will be constantly slapping the pavement and the tire will go downhill very quickly.
Constant vibration like this can often lead to squeaks/rattles, screws and nuts working loose, and failure of some electrical items.
Yeah, I agree.
In years gone by, when we all drove bias ply tires, tire stores had “truing” machines that could skim-cut the tread and round out the tire, but I doubt if you could find one today. Most of the people working at the tire store probably have never even heard of one.
I would suggest replacing them. Remember that the best tyres should be on the back wheels, if you don’t have all four matched.
You might be able to shave the tyres, but then you would not likely have much wear left. I don’t think it would be worth it.
What is it called: what I mean is: I fully believe that “the best tires go in the rear” But in my 55 years on the planet I have never had a discussion with anbody that stated “if only the best tires were on the rear” , none of the employees at body shops next too any of the Dealers I worked at ever made a statement “another case of best tires on the front” in short this situation has never come up any where but here.
I had a undertaker friend that picked up plenty of dead people (dead from car wrecks) and never was the cause of the crash stated to be “wrong tires in the wrong place” Now I have seen plenty of totaled cars with blown out tires,tires that were so bad the only place they should be is stacked somewhere, so what is a situation called that is technically true but is never (at least to me) pointed out as the cause of the accident?
I agree that the tires need to be replaced and that the best tires always need to be on the rear. Jack-knifing a vehicle is the cause of a lot of vehicle accidents and are behind most of the “driver lost control” reports.
I’m 70 years old and in mt younger days I was Fast foolish and broke. I experienced a few blowouts in the 100 mph range an believe me, a rear blowout is much more dangerous than a front one. With a front blowout, as long as you stay off the brake and keep a grip on the wheel,the tire vibrates and the friction quickly slows you down. A rear blowout throws you all over the road.
Wow, thank you all so much! I stumbled upon Car Talk reading an NPR discussion and I will happily be tuning in when I can. It looks like you have built a great community here - kudos 
As for the tires, I’ll make sure we get them replaced a.s.a.p.
Junk the tires. At least with a Sentra there are many choices and affordable ones too.
Sorry your car is old that it does not have ABS and would have prevented this problem.
If your tires have a warranty/road hazard coverage, you can probably get them replaced for free or at least at a pro-rated rate.
Does the car have ABS? If so, how did she manage to skid far enough to get flat spots?
We are talking about tires with 2/32 tread difference to be considered “the good set” not “maypops” or the type you avoid running over lit cigarettes with.
No, it does not have ABS 
Thanks again for the great info all!