A take-apart tire and wheel assembly including a multi-piece wheel rim having axially spaced bead flanges, a rim base, and a pneumatic tubeless tire, preferably adapted to removably receive in its tire inflation chamber a safety runflat insert. The wheel assembly also includes a safety vent for preventing inflation of the tire cavity in the event of improper assembly or disassembly of the safety tire and wheel assembly, including an O-ring seal disposed between opposing portions of rim segments of the wheel assembly, and mounting studs and associated nuts that releasably clamp the rim segments together with the O-ring captured in compression therebetween. The outboard wheel rim segment includes a wheel mounting disc and also a safety inflation valve coupling fixed to the outboard rim segment. The rim segment and coupling each have a through passageway and together define an interior air passage which communicates with the tire cavity. At least one of the through passageways is permanently connected to the rim segment and has a safety control cross sectional configuration adapted to prevent passage therethrough of an air inflation valve provided on an inner tube of sufficient size to fit within said tire cavity and capable when inflated of rendering said wheel and tire assembly normally operable for supporting its normal vehicle load in a run-mode of the vehicle. The safety inflation valve coupling and rim segment are thus operable to prevent insertion of such an inner tube valve through the one passageway permanently rim-connected. The coupling itself may be permanently or removably connected to the rim segment.