Cargo, Securement, and Weight Limits
Securement
Cargo must not shift. Use at least one tie-down per 10 feet of cargo, with a minimum of two. Aggregate working load limit (WLL) must be at least 50% of the cargo weight. Use a front-end structure or header board. Recheck within the first 50 miles and every 150 miles or 3 hours.
Weight
Federal limits: 80,000 lb gross, 20,000 lb single axle, 34,000 lb tandem. The bridge formula limits axle spacing. Never exceed tire ratings.
Worked example
A 30-foot load weighs 12,000 lb. Minimum tie-downs: 30/10 = 3. Aggregate WLL needed: 50% × 12,000 = 6,000 lb. Three straps rated 2,000 lb WLL each give 6,000 lb, just meeting the rule. Reasoning: both the count and the strength must pass.
Traps
Counting straps without WLL; using damaged straps; forgetting the 50-mile recheck; overloading an axle while under gross.