Steve,
One other item to consider is tire stencils. Replicas & Miniatures Co. of Maryland, Norm Veber's company, has photoetched tire stencils for almost any application.
I use a great majority of his detailing supplies and his quality is top notch.
His last price list has a F-1 tire stencil listed (item RM-50) for 1/20th scale kits.
To use these stencils is simple: you place the stencil on the tire, secure it with light tack tape, and then spray the desired color. You could then dull coat the tire to seal the paint on if you wish. Remember to wipe that tire good so there is no mold release or other barrier left on the rubber tire.
I know Norm is very busy prepping for the NNL East but you could shoot him an email at
replmincomd@aol.com
He is running around a week to ten days in filling orders. That is what he told me yesterday when I spoke with him about his Ardun heads for a ford flathead.
Hope this helps...