The converse is true of the radial. Its sidewall flexes easily and there’s little or no friction between the belts, so less heat is created, which, if nothing else, makes the radial a more durable tire. But radials enjoy other advantages as well. Because the radial is more flexible, it creates a larger contact patch, which increases traction. Furthermore, because the belts of a bias tread crisscross each other, they tend to make the tread squirm slightly as the contact patch impacts the pavement. This contributes heat and increases wear on the tire. Because the tread of a radial tire is braced by reinforcing belts, it unrolls in a straight line, much as a rigid caterpillar track does, which decreases temperature and wear. So while there’s nothing inherently wrong with a bias belted tire (overall, they work just fine), the radial is simply a more efficient design that works better.