Log Truck Payload and Legal Load Volume

An 80,000 lb legal gross behind a 32,000 lb tare leaves 48,000 lb of payload, and on green Douglas-fir at 10,500 lb per thousand board feet that is a 4.57 MBF legal load. THE SAME TRUCK ON GREEN RED OAK at 13,000 lb/MBF is legal at 3.69 MBF -- 0.88 MBF less, on the same truck, on the same road, because the wood is heavier. A loader working to a habitual stake height rather than to a weight will put the oak load 11,429 lb over the payload, which is a citation and an off-load at the roadside. SEASONING CUTS THE OTHER WAY: the same oak decked through a dry summer at 11,000 lb/MBF takes the legal load back up to 4.36 MBF. A mill scaling loads that vary this much without tracking species and deck time is not going to reconcile its wood against its tally. THE AXLE LIMITS ARE THE ONES THAT ACTUALLY CATCH TRUCKS. The gross limit is the one everyone quotes, but a load within it can still be over on a tandem or a bridge-formula group if it is placed wrong, and weight distribution on a log load is set by where the butt ends sit -- a loader decision made in seconds. The useful field form is the inversion: given the tare and the legal gross, how much of THIS wood is a legal load, which is a number the loader operator can work to directly. A payload subtraction. It does not address axle group limits or the federal bridge formula, which frequently govern below the gross limit and depend on axle spacing and load placement rather than total weight. It does not address state and local variations in legal gross, permit loads, seasonal frost-law reductions, or the reduced limits that apply on many forest and county roads. Green weight per thousand board feet is highly variable and published figures are broad ranges -- a region's own measured conversion is far better. It does not address load securement, a separate regulated matter with its own requirements for logs specifically. The applicable state and federal weight limits, the bridge formula, FMCSA securement requirements for logs, and the scaling rule in use govern.

payload = legal gross weight - tare weight; the legal load in thousand board feet = payload / the green weight per thousand board feet for the species and condition; the habit overload = the legal load of the lighter wood x the heavier wood's weight per MBF, less the payload.

The payload relation by name, with the federal bridge formula and the FMCSA log securement requirements named as separate matters this does not evaluate. The applicable state and federal weight limits, the bridge formula, FMCSA securement requirements for logs, and the scaling rule in use govern.

Subtraction and division on the truck's own tare and the region's own green weight conversion; no state weight table is reproduced.

Estimate. AHJ and licensed professional govern.

Field names used by the API: legal_gross_lb, tare_lb, weight_per_mbf_lb, alt_weight_per_mbf_lb, seasoned_weight_per_mbf_lb, load_volume_mbf, payload_lb, legal_load_mbf, alt_legal_load_mbf, seasoned_legal_load_mbf, mbf_difference, overload_if_habit_lb, entered_load_lb, margin_lb

• Axle groups often govern below the gross a load legal on gross can be illegal on a tandem or a bridge-formula groupthe federal bridge formula
• Green weight per MBF is a broad range a region's own measured conversion is far better than a published figureregional scaling practice
• Securement is separate and regulated log loads have their own FMCSA requirementsFMCSA