Western Australian Current Regulations Western Australian Current Regulations (1) In this
regulation —
combination means a combination that includes a
heavy vehicle.
(2) The total mass of
a combination, other than a road train or B‑double, and its load, must
not exceed 42.5 t.
(3) The loaded mass of
a dog trailer or pig trailer must not exceed the loaded mass of the towing
vehicle.
(4) The total mass of
a combination and its load must not exceed the towing vehicle’s GCM.
(5) If the
manufacturer of a motor vehicle forming part of a road train or B‑double
has not determined the GCM of the vehicle, the total mass of the combination
and its load must not exceed the amount, in kilograms, equal to A in the
formula —
where —
K is —
(a)
0.055 if a single drive axle is fitted to the motor vehicle; or
(b)
0.053 if a single drive tandem axle group is
fitted to the motor vehicle; or
(c)
0.051 if a dual drive tandem axle group is fitted
to the motor vehicle;
M is the number of
tyre revolutions per km as specified by the tyre manufacturer for the tyres
fitted to the driving axle or axles;
R is the overall gear
reduction between engine and drive wheels;
T is the maximum
engine net torque in N m.