In terms of the contents measured in Dollars, it would depend upon many different factors. The primary factor being the actual value of the goods inside the trailer.
In terms of volume,
A 53 foot truck trailer can hold 26 standard sized pallets on the floor.
A 48 foot truck trailer can hold 24 standard sized pallets on the floor.
The term “truckload” doesn’t always mean the trailer is full. Typically, a shipment of 8 pallets or more at one time, will have to ship at a truckload rate.
It is common, and wise, to double stack short pallets (4 foot height) to further fill a trailer. This means one pallet is placed on top of another. The more merchandise you can ship for the same freight expense the more profit you will realize after your sale.