Tire Marks from standing still?

Any Idea what is going on here. I had a new garage built, and now 2 months later I am getting track marks, (4 treads) sticking to the concrete from the front tires only of one car. Both cars have the same tires, purchased from the same place, at the same time. And only one leaves marks. The last 10 minutes of our slow drives home are also identical. It seams to be leaving a good bit of tread behind that you can wipe onto your finger like a powder.

I had a picture of it posted here:
http://asmclaughlin.tripod.com/

-Mike

What's being left behind is ON the tire when it arrives at your garage - notice that you have the outline of the tread pattern and only part of it at that - and always the same part.

I would be looking for tar or newly paved asphalt on the route that particular car makes.

It's also possible that you had some of it on the tires that is gradually being "dripped" off - at least that wouls account for the difference in intensity between the marks. So look at the tires and see if you can see something on them.

Hope this helps.