A method for improving the radial enlargeability and other properties of tape-reinforced tubular vascular graft formed of sintered fluoropolymer(s), such as expanded, sintered PTFE. Broadly, the method comprises the step of radially shrinking the reinforcement tape layer of the graft, or the entire tape-reinforced graft, after sintering thereof. Such radial shrinkage of the reinforcement tape layer, or of the entire graft, renders the graft subsequently radially enlargeable by more than 5%, without tearing or breaking of the reinforcement tape layer of the graft. Radially enlargeable grafts of the present invention may be combined with various types of stents or anchoring systems, to form endovascular graft devices which are transluminally insertable and implantable within the lumen of a host blood vessel. Alternatively, radially enlargeable grafts of the present invention may be implanted by way of traditional surgical graft implantation techniques, without any radial enlargement of the graft at the time of implantation, so as to take advantage of the improved strength properties and suture-holding properties of the radially-shrunken tape-reinforced grafts of the present invention.