FORD 2009 F-550 v.1 - Manual (Page 288)

Recommended shift speeds
Do not overspeed the engine when going downhill or steep grades. If
equipped, use the tachometer and do not allow engine speed to exceed
the redline area. Operating the engine beyond the recommended speeds
can cause severe engine damage.
Shift according to the following shift speed charts:
Upshifts when accelerating (recommended for best fuel
economy)
6-speed transmission
Shift from: Transfer case position 1 (if equipped)
2H or 4H 4L
LO-1 5 mph (8 km/h) 2 mph (3 km/h)
1-2 14 mph (23 km/h) 6 mph (10 km/h)
2-3 22 mph (35 km/h) 9 mph (14 km/h)
3-4 30 mph (48 km/h) 12 mph (19 km/h)
4 - D
(Overdrive)
40 mph (64 km/h) 15 mph (24 km/h)
Maximum downshift speeds 1
6-speed transmission
Shift from: Transfer case position (if equipped) 2
2H or 4H 4L
D (Overdrive) -
4
45 mph (72 km/h) 16 mph (26 km/h)
4-3 35 mph (56 km/h) 12 mph (19 km/h)
3-2 20 mph (32 km/h) 8 mph (13 km/h)
2-1 5 mph (8 km/h) 2 mph (3 km/h)
1-LO Only shift to LO when at a stop.
1 Use 2H or 4H for 4WD equipped vehicles.
2 Downshift at lower speeds when driving on slippery surfaces.
2009 F-250/350/450/550 (f23)
Owners Guide, 1st Printing
USA (fus)
Driving
288