Flexible tubing or hose is formed from continuously extruded thermoplastic material helically circumferentially wound at a wrapping station around an array of bearing-supported rods that are concurrently but individually turned and are canted relative to an imaginary central axis. The tubing or hose is formed to have a continuous reinforcing rib helically wound therearound and continuously integrally connected thereto. The positions of the rods are progressively altered during formation of at least a contiguous portion of the tubing or hose, causing the resulting contiguous portion to exhibit a progressive continuous change in diameter. The resulting tubing or hose may be transversely severed at intervals along its length, and may be flattened to form cuffs near where severed. A selected portion of the tubing or hose, which may or may not at least partially coincide with the contiguous portion, may be axially compressed and annealed to relieve stress therein.