tick tick tick
 

I noticed this a few times, but I really noticed it yesterday. When I pull down my window I can hear a tick tick tick sound that seems to come from the outside left side (my left) when the car is moving. I couldn't make out where it was coming from. It was one of the first really cool days of the season o I'm wondering if that may have something to do with it. I noticed later on, when I started the car hours later and left the heater on for a while, that the ticking seemed to have disappeared.

Any ideas as to what it might be. I'm due to take the car in for service soon, but I wonder if this could be important enough to move it up.

It could just be a small rock stuck in the tire tread.

I was thinking that was a possibility. I'm always pulling out rocks from the thread and there is a lot of construction around where I live. I hope that's all there is to it.