Feet, Metres or some on the number of wheels the truck has eg. 12 wheeler
A metre.
It would be normal to use either meters or feet, but you can use any unit for length (inches, cm, mm, km, etc.)
Feet would be nice, or meters where the metric system reigns.
By unit of length and distance and conversion ,we can say that the most appropriate unit to measure the length of a finger is cm.
tons
Tonnes
Inches
cm
always the meter to measure length. This is an SI (international) unit of measurment, and is the standard international unit of measurment for length.
I would use feet
You would use meters.
yards