2.6 A 3200-lb car (Cp = 0.35, Af= 25 ft^2, and p = 0.002378 slugs/ft^3) has 14-inch-radius wheels, a drivetrain 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.)