It could be a flap of rubber hanging off the tread. That is most commonly the problem. It could also be that there is a rock in the tread or in the tire itself. Someone could have accidently dropped one in there if you had the tires replaced. Check the tread and make sure there is no rocks in it.
The tapping sound in your tire could be caused by a rock in between the tire treads. Try to determine what tire the noise is coming from. Look closely between the tire treads, or use hands and feel in between the treads. You may have to move the vehicle forward or back to be able to check the whole tire.
If you're sure it is coming from your tire you need to take it into the shop ASAP as it could be a lose or torn belt. If this is the case the tire could shred or explode easily causing damage to your car or causing an accident.
Is it a clicking sound while moving, that speeds up as you go faster, and vice versa? It might be a rock stuck in the tread that's clicking on the pavement. It could also be a worn out wheel bearing or CV axle.
It could be a flat tire, I would check that first because it's easiest. Just drive your car on a level road and while driving slowly, let the wheel go and if it tilts to the side, a wheel is flat! Also, it could be your axel.