Bias ply tires are a type of tire construction where layers of fabric, known as plies, are laid at angles to each other. This design provides a flexible sidewall, which can enhance ride comfort and traction on rough surfaces. Bias ply tires are often used in vintage vehicles and certain off-road applications due to their durability. However, bias ply tires generally have less stability at high speeds compared to radial tires, which have plies arranged in a radial pattern. As a result, they may not be the best choice for modern vehicles that require high-speed performance and handling.