2.6 A 3200-lb car (Cp = 0.35, Af = 25 ft, and p = 0.002378 slugs/ft3) has 14-inch-radius wheels, a drive train efficiency of 93%, an overall gear reduction ratio

of 3.2 to 1, and drive axle slippage of 3.5%. The engine develops a maximum torque of 210 ft-lb at 3600 rev/min. What is the maximum grade this vehicle could ascend, on a paved surface, while the engine is developing maximum torque? (Assume that the available tractive effort is the engine-generated tractive effort.)