A bulk tank trailer including an interior storage compartment, at least one straight rear wheel axle supporting a plurality of ground-engaging wheels and a longitudinally aligned discharge pipe in operative communication with the interior storage compartment is disclosed. The entire discharge pipe may be positioned above a transverse plane of the at least one straight rear wheel axle. A method of discharging particulate materials is also disclosed. The method includes filling an interior storage compartment on a bulk tank trailer with the particulate materials, positioning a straight discharge pipe above a straight rear wheel axle on the bulk tank trailer, moving the particulate materials from the interior storage compartment along the straight discharge pipe and discharging the particulate materials from the discharge pipe.