[Zeke]

Back to the flat spots. You can tell if this is the problem by lifting the car and letting it sit for awhile. A nice warm day will help. After the tires have relaxed, spin them and watch the tread with something for a referrence, like a ruler across a pair of jack stands just off the face of the tire tread. Tires shops sometimes have a large version of a dial indicator for this very purpose. It has to have a fairly large follower wheel to span all the agressive tread patterns of the day.

That's why the ruler might work just as well. Now, if your tires are flatted, finding someone with a shaver will be the next problem. And, if you do, he may not want to shave a used tire because of embeded debris that will ruin his shaver disc.

You, know a couple of new tires just aren't that expensive to go thru all that. But it can be done. Sell the old ones on your local list to someone that drives a beater and could use some fresh tires on the cheap.