Due to their soft sidewalls, the crowns of radial tyres stick to the road on contact. Their imprint, shorter but wider than that of a bias tyre, provides added grip when leaning in heavily on corners. The pressure of the air in contact with the tyre surface is distributed more effectively with radial tyres, which results in more even tread wear over time.
Radial tyres also provide greater comfort at higher speeds, once again as a result of their soft sidewalls, which absorb the impact of imperfections on the road surface. On the other hand, bias tyres are able to carry a greater weight because their sidewalls are more rigid. At high speeds, bias tyres can become so deformed that their performance is affected.
Ultimately, bias tyres are suitable for vehicles travelling at moderate speeds, with small to medium-sized engines and flexible chassis. They are also suited to heavy motorcycles or those that are heavily loaded.
Radial tyres are needed for more powerful vehicles with very rigid chassis and for more sporty purposes. They allow you to reach ZR speed ratings, above 240 km/h.