If a vehicle has wheels and tyres with a rolling radius of 0.315m and the engine is producing a torque of 150nm at 4000 rev/min in fourth gear.

(matching 4th gears have 30 (driver) and 29 (driven) teeth. Final drive gears have 20 (driver) and 88 (driven) teeth.

am i correct in thinking final gear ratio is 29/30 x 88/20 = 4.2:1 (1st dp) ???

i need to...

i. Calculate the speed of the vehicle(km/h)
ii. Calculate the tractive effort produced at the road wheels.

I would be grateful for simple formula a dummie can understand... thanx