I was wondering how you all paint large truck tires? I normally use a stencil for painting my roadwheels on tanks but I'm looking for a trick that will work for large tires. Also, how exactly do you create the effect where you have "dirt" in the inside of the tread of the tire and a clean surface on the top where the tire makes contact with the ground?

I paint the whole wheel and tyre my base color. Then I use a dark grey wash and run it around the Tyre bead and paint the whole tyre with it. Dry brush pure black around the road surface area of the tyre and then wash with your favourite dirt color making sure that you leave plenty in between the treads.

Cheers
Cliff

Yep, I do basicly the same as Cliff.

Ditto to Cliff and Dave's method.
These are not large truck tires, but rather large scale motorcycle wheels.

That's exactly what I was talking about thanks for the tips. I was curious how you all kept such perfect lines around the rim and bead of the tire? I was thinking about painting the wheel the base color and coating it in future in case I slip with a brush so I can easily wipe it off. Do you all think that will work?

No need as the wash is thin enough to capillery action around the bead by itself so there is less chance of mistakes. Besides if you slip just let it dry and touch up with base color.

Also if the base coat is enamel I use an acrylic wash and vise versa so the thinner used to make the wash is different to the base thinner. This way the wash will not lift the base coat.

Cheers
Cliff

For a more prototypical look, you could try not masking at all. It's not as pretty, but more often than not, this is what I find: