The model didn't look right... A Jeep with smooth tires... Luckily, the tire tread was a distinct material, but how? First, tires aren't as black as some think. So adjust the colour a little and turn down the specular colour. Unless somebody has been really tarting up their tires, or it's wet rubber, it isn't going to shine. Second, and this is the quick trick, I applied the Weave 2D Texture option to the tread area, as a displacement map. A bit of fiddling with the UV scaling, and the amount of displacement, and suddenly the tread wasn't smooth and pervy any more. But don't get too close.

Nice quick hack. :)