Vehicle Characteristics and Handling of Medium Vehicles
Size, weight and pivot points
A medium truck is roughly 2.2–2.5 m wide, often over 3 m tall, with a long wheelbase and rear overhang. The rear wheels track inside the front wheels, so 内輪差 on a left turn can put the rear tyre onto the kerb or across a cyclist. The rear overhang also swings outward as the turn begins.
Weight transfer and centre of gravity
Load raises the centre of gravity. In a bend, centrifugal force rises with the square of speed while rollover resistance falls as the centre of gravity rises, so a loaded truck can tip at a speed that felt safe empty. Braking transfers weight forward, unloading the rear axle and lengthening the stop.
Brakes and drivetrain
Many medium goods vehicles use air-over-hydraulic or full air brakes: pressure must build before moving, and air tanks need draining. Engine braking and exhaust brakes spare the service brakes on long descents; riding the brake overheats it and causes fade.
Worked example
A left turn at an intersection: the front wheels clear the kerb by 0.5 m, but the rear inner wheel cuts 1.5 m inside the front track. Reason: the rear axle follows a shorter radius. The driver must swing wider before turning, then check the left mirror and blind spot for a cyclist in that 1.5 m band.
Traps
Judging width from the cab; turning early and trusting the mirror alone; forgetting the rear overhang sweep; assuming ABS shortens stopping distance on ice.