I have a set of new Michelin PSS tires that have been balanced at a local race shop and are giving me a vibration in the steering wheel. I took the wheels back to the shop to check the balance and it was spot on, but we noticed at that time a dip or flat spot in the tread of both front tires. It is not large, maybe about 1/32, but is visible to the naked eye as the tire rotates on the balance machine. The rims are true. The question is, how much variation is considered acceptable in a factory fresh tire? Do tires "wear in"? They are really fresh, as in made only weeks ago. The Michelin break in guide says that it can take up to 500 miles for a new tire to "deliver their normal ride quality and maximum performance" The Tire Rack is still considering what to do, but not immediately deciding to replace the tires. They are stock sizes (235/40/18) on 8.5 inch rims.