A tire insert for vehicle wheel which has an annular element made in one piece of polymer material is provided. The annular element has a base portion suitable for being accommodated in a rim seat of a rim and an enlarged portion having a section larger than the base portion. The enlarged portion is shaped to have shape and size to always be spaced apart from an inner tire side when the tire is inflated to a predetermined standard working pressure. When the tire is deflated, the enlarged portion comes into contact with the tire to support the tire while the vehicle wheel is running. A vehicle wheel having a tire, a rim onto which the tire is mounted, and the tire insert is also provided.