Nu-Tek 700 x 20 TT (TT = 120PSI Tire) Airless Solid Black Bicycle Tire w/Speed/TT Tread. Nu-Tek 700 x 20 TT (TT = 120PSI Tire) Airless Solid Black Bicycle Tire w/Speed/TT Tread. Guaranteed never to go flat!! Maintenance free - no need for inner tubes, air pumps and puncture (repair) kits. High resistance to wear and tear. Independent Laboratory tests have shown expected life span two to four times longer than a rubber tire. Weight - equal to or less than pneumatic tire and tube. Loose the pump, patch kit and problems associated with rusty nails, broken glass and thorns! Nu-Tek tires are manufactured in the USA which is unique since United States production of bicycle tires was totally discontinued in 1987.