Tire color

I like to use Pactra Hot Rod Primer Gray or RLM 66 on my models. Part of my job is transfering tread patterns to cardboard. I use a semi gloss black to do that. The paint is always darker than the tire.

I recently found a paint I like very much for aircraft tires. Its an acrylic from the Color of Eagles line called Tire Black. Very realistic shade of dark gray. The a/c in my signature pic is painted in that color, with semigloss black hubs.

Dana,
Like you, the only color I've ever used is flat black. But after drying, I like to take a light earth tone, or maybe a real light gray, and gently dry brush both the wall and tread of the tire. I've had other modelers tell me that since dirt only really gets on the treads, I shouldn't dry brush so much on the side walls, but the heightened effect of deepened detail I get is just too good to pass up. Sidewall drybrushing is really good when you have raised letter detail, and tread that comes over onto the sidewall.
Gip Winecoff