Painting Road Wheels?

i've did this once with my Challenger tank. What I did was after spraying the wheels, i masked the wheels, then just cut away the excess tape covering the tyres, after which i sprayed black over the wheels. turned out fine though

I tried the masking technique on my current M1A1 project. I did a few this way and then tried something different.

I felt it was easier to paint the entire wheel in my base color then, put the wheel on a toothpick (use some masking tape rolled on the toothpick to make the wheel snug) hold a brush dipped in thinned black / gunmetal and just twist the toothpick.

I'd recommend what Erock suggest. Any 'accidents' can easili be covered with dust, mud,..whatever. If you insist on airbrushing them, try the opposite: spray the rims first, then use circular templates as found in art stores or on some PE sheets to cover the rims and spray the inside of the wheels.

Wouldn't it be nice if wheel and tire were seperate?

if you look at a crafts store the type your wife or girlfriend might go to, look for these lil' circle stickers, they work wonders for road wheels.
all you have to do is by the correct size then stick it on and spray away, remove then voila! instant roadwheel. I stand corrected from an easdropping wife, it's in the office supply section!

Just my $.02 worth....
I don't mask--it takes too long...
Spray the entire roadwheel flat black. Next, spray the base color on the wheel portion as if you were trying to spray on polka-dots; use a fine airbrush setting. Allow the dots to overlap so that the black shows through only slightly. This gives the paint a weathered/faded look from the get-go. When dry, use a black, or other dark wash at the rim/tire joint (I do this when I wash the entire tank.). This effectively covers/removes any overspray. Easy. I've had good success with this method for the last 10 years or so.
Gip Winecoff

claymore 68,
BTW, Academy has made their Merkava series with separate wheels and tires. The tires are a rubbery vinyl and seem to work OK. They can be a little difficult to weather (I don't think I prepped mine as well as I could have.)
GW

I simply airbrush the entire wheel with a black/grey mixture and then use the circle template to paint the hubs. If any overspray occurs I usually touch up with a much thinner black/grey mixture to get capalary action around the center hub. I think it works quite well.

Cheers

Rob