The advantages to bias tires are stiffer side walls, which make them tougher and more resistant to damage from curbs or rough applications such as farm use. Bias tire mileage is lower compared to radial, but for lower speeds and less frequent use they provide a more economical choice. Lug Circle Diameter: 4.5â Wheel Ply: 4 Wheel Sidewall Height: 4.8â 480 x 12B Bias Trailer Tire.