I believe they came about in the late prewar or early postwar era. And, there was also the Lightning Sidewall tire, aka the snakebelly tire. The Darts were made as replacement tires through the 60s, and I guess they dusted off the old molds for Murray's Monterey in 1978. There's a thread on the Cabe, of folks petitoning Carlisle to either make more tires, or sell the molds to someone who will. But, they apparently aren't interested. -Adam