That's generally in the mountains; I know the CHP enforces it in the mountain passes--a friend of mine who used to live in Kahleefohneeya (and says he'll never return because several of his rifles are no longer legal there, despite originally being purchased there) told me about the CHP forcing him to put snow chains on the rear wheels of his FWD car... There aren't many places in Oklahoma where you'd need 4WD or chains to access something by road.Not sure about out here, but there are Highways that are impassable unless you have 4x4 and chains. Highway patrol enforced...