A tundra tire (UK: tundra tyre) is a large low-pressure tire used on light aircraft to allow operations on rough terrain. A common variant of tundra tire is the bushwheel brand. These tires include an integral inner tube with the valve manufactured into the side-wall, allowing the tire to operate at very low pressures without risking shearing-off the valve stem and causing a flat tire. Low-pressure tires provide greater cushioning and enable aircraft to land on rough surfaces, unsuitable for normal tires. Bushwheels are a common modification for backcountry aircraft. History The tundra-style tire has been independently invented at different times and places. In North America its post-World War II invention is credited to Canadian Welland Phipps, potentially inspired by the Goodyear Tire & Rubber Company's pre-World War II development of their own, similar low-pressure "airwheel" as a complete wheel-rim and tire set — said to be of the "Musselman" type from , for its original inventor, Alvin J. Musselman — which was introduced to the American public in the late summer of 1929, and becoming available in the United Kingdom by 1930. It was initially offered by Goodyear in fully inflated diameters up to 46 inches (117 cm), with a thirty-inch (76 cm) diameter in Goodyear's lineup having similar dimensions as seen in the British Flight magazine announcement, to a currently available size of tundra tire. Nearly twenty years after the original Musselman design appeared on the market, Phipps designed and constructed his own balloon tires in the period after the Second World War and fitted them to a Piper PA-18 Super Cub. Phipps then went on to provide air transportation to much of the Canadian high arctic region. He later established his own airline, Atlas Aviation, which operated a fleet of De Havilland Canada DHC-6 Twin Otters on balloon tires. Using the tires, Atlas's DHC-6s established airline service to such remote communities as Resolute, Nunavut and Grise Fiord, Nunavut. Airworthiness issues In the United States and particularly in Alaska, tundra tires of various designs were often installed under local field approvals by Federal Aviation Administration inspectors. These approvals were usually granted on the basis of visual inspections and did not include flight testing. After a number of accidents with aircraft equipped with tundra tires, culminating with a large number in the fall of 1994, the National Transportation Safety Board identified that the tundra tires were connected with the