Looking for tips on weathering tires

I posted this in the replica stock catagory as I am not sure where it fits better. I have a few kits that I want to make into junkers and want to know how to weather the tires. Some kits have the rubber tires like tamiya and others ther vinyl as amt kits. I want to make some flats or just old looking tires. Some are 2 piece like with white walls on classic cars. Any help would be great.

Source: http://cs.scaleautomag.com/SCACS/forums/thread/956104.aspx

Menato Boffa Bob Bondurant Felice Bonetto Jo Bonnier Roberto Bonomi