Tires: Tire Problems, les schwab, tire problem

Question
I recently purchased a 1983 Suburban that wasn't running.  It was relatively cheap to get it running.  When I drove on the freeway I knew I had some sort of tire problem.  I took it to Les Schwab and they told me that all four tires are dangerously out of round.  This has been confirmed by another mechanic.  When I asked why it was dangerous to drive on out of round tires all they could say is that it is dangerous.  What are the dangers of driving on a, or four, tires that are out of round.

Answer
Thomas,

What happens when a tire is out of balance or out of round is that the axle moves up and down - loading and unloading the tire.  When this is small it isn't much of a problem - except it is annoying.

But when it is severe, the tire could leave the road surface - and you would not have any grip during that time.  That means that even under the best of circumstances, your braking distance will be greatly increased.  This would also affect your cornering ability, which under emergency conditions is not something you want compromised.