What is a polybonded steel radial?
The next-generation radial tyre for passenger cars which uses polyester plies in its construction

A polybonded steel radial is a next-generation radial tyre for passenger cars. Unlike ordinary radials which use nylon cord, polybonded radials feature polyester plies in its construction.

Nylon is affected by temperature, climate and age but polyester is not. Thus, while other radials lose shape over use, polybonded steel radials retain their dimensional stability throughout their life.