In case you're interested, I once had a customs agent get out of his booth and look at my tires. He then asked if I had any work done on the car that I hadn't declared. They were a line carried only by Canadian Tire so that was the end of the discussion. .
Tires have a red and yellow painted dot to guide the installer to correctly install them. Red dot by the valve stem is suggested but it's ok even if the tire store ignores them. I suppose some people might bring some soap or rubbing alcohol to rub off the dots in order to make the tires look old. Others might even add some mud to the sidewalls.