In Ireland, timber and biomass haulage faces the challenge of transporting enough material within strict legal dimensions and gross vehicle weights restrictions for trucks and trailers. The objective of this study was to develop a method to control payload weight by knowing the moisture content of the wood. Weights, volumes, and moisture content were gathered from 100 truckloads of Sitka spruce pulpwood. Truck volume and weight utilization patterns were analyzed based on stacked volume, truck volume, and weights recorded from the weighbridge. Solid/bulk volume conversion factors for the truckloads were estimated indicating the truck’s solid volume capacity to be filled. Trucks were grouped into five conditions based on their configuration—volume capacity and legal maximum payload. A loaded volume fraction was estimated to assess the optimal volume capacity and stanchion height at which the trucks should be loaded. Results showed that 100% of the trucks presented volume underutilization, with a maximum of 27.5 m3 (only 39.85% volume capacity). In contrast, 67% of trucks were overweight while the remaining 33% were under the legal maximum weight. The average solid/bulk volume conversion factor was 0.66 ± 0.013 at 95% confidence level. Depending on the conditions, trucks can be filled to 100% of their volume capacity with wood at an MC from 29% to 55%. The minimum truck volume capacity utilization was 45%. This methodology can be used by truck hauliers, enabling them to determine in-forest the optimum volume and weight of wood to be transported by knowing the moisture content (MC), the wood specie, and using the height of the stanchions of the trailer as reference when loading the truck.