The present disclosure relates generally to flexible tubing, for example, suitable for use in peristaltic pumps. The present disclosure relates more particularly to flexible tubing having a stable flow rate despite being extruded from thermoplastic polymer and methods for making such tubing. In one aspect, at least 50% of the material volume of a flexible tubing of the disclosure is formed from a first polymer material that includes a continuous phase that includes polypropylene and a non-cross-linked styrene block copolymer elastomer miscible with the polypropylene, as well as, dispersed within the continuous phase (e.g., discontinuously dispersed within the continuous phase), a cross-linked rubber phase. The non-cross-linked styrene block copolymer elastomer is present in the first polymeric material in an amount in the range of 2 wt % to 15 wt %. In certain desirable embodiments of the flexible tubings described herein, the flexible tubing has a flow rate variation over the 480 hours of use of less than 20%.