how much tread should u have on a tire? i remember something about using a penny but dont remember exaclty what. i only have 14k miles on my tc's tires but they looking pretty bad.

Thats because tC's come with junk tires IMO.
The penny thing...the tread should come to the top of Lincolns head.
You'd probably get the best info by checking out the tC wheel & tire forum.