Good Year Lifeguard tires... two ply inner tire inside the regular tube, both inflated by the same valve. When the casing blows out only the outer tube goes.

The inner tire held enough air to support the car until you could come to o safe stop, instead of a blowout so severely upsetting the car's handling that it was likely to cause a crash

http://www.retro.red/goodyear-lifeguard-tires/