How can I tell if tires have flat spots or broken belts?

It sounds like I have a flat spot on my tires because it makes a weird noise that is speed (not RPM) dependant. Left the car sitting for about 6 months without driving it that much until February. However, it just started recently, or I just noticed that it makes a whomp, whomp, whomp, sound the faster I go. The car seems to handle ok, it's just that the noise is annoying.

Can any tire place check out the tires to see if they are flat spotted or if a belt broke, or would I need to go to a place that has a specialized balancing machine? The tires look ok, and I dont think any wheel weights fell off. If a shock went bad, wouldnt it be really noticeable? I didnt see any sign of oil on the struts when I took the tires off to check them.

 

I took them off and the rear tires are wobbling a little. They are about 3 years old and have 10,000 miles on them. Changed rims and tires to an old spare set that is dry rotted and 7 years old that I keep as a backup in case of a flat and it still makes the noise but not quite as bad, however, one of the spares tires wobbled too.

Talked to my old next door neighbor that owns a tire shop for semi trucks, and he said that he has a high speed balancer for cars in his shop since he also does passenger cars for commercial accounts. So tommorrow, I am taking the wheels there and seeing if they are in balance.

 

Found the problem.

The wheel in question had a very small amount of runoff on it. Dont know how this happenned since I never hit or ran anything over anything. But the main problems was that all the tires were out of balance. The fronts were only off by 1/4 of an ounce after the weights were taken off, but the rears were off a lot- one was off by 3.5 ounces- That's like adding a quarter pounder to your wheel!

Instead of adding all that weight, we took the tire and rotated it around on the rim so that the least amount of weight would be added. It took a while to do this, because we had to find out how what weights were needed on the inside and outside area, and then mark it and then rotate the tire around so that the heavy section of the tire would offset where weights needed to be added. After doing this the wheel in question only needed .75 ounces of weight to be added.

I put the tires on and now the problem is solved!