Since the pneumatic farm tire was developed, the basic carcass construction has been bias or diagonal plies. As tractor manufacturers continue to produce models with higher and higher horsepower, it has become evident that the conventional design changes--lug shape, lug angle, aspect ratio, etc.--are no longer sufficient to achieve significant improvements in tractor drive wheel tire performance. After investigating various alternatives, B.F.Goodrich determined that a radial construction offered distinct performance advantages over a bias construction without requiring any redesigning of the tractor. These include: increased traction, reduced fuel consumption, longer wear and improved ride. This paper will present comparative performance results of radial and bias drive wheel tractor tires, and discuss the basic radial tire mechanics which make the performance improvements possible.