Federal Weight Limits
The Federal Highway Administration sets maximum weight limits for vehicles operating on the Interstate Highway System. These are the absolute maximums — many states impose lower limits on state roads.
80,000 lbs
Maximum Gross Vehicle Weight
Total combined weight of truck, trailer, cargo, fuel, and driver
12,000 lbs
Steer Axle Maximum
Front axle of the tractor (industry standard, not federal law)
20,000 lbs
Single Axle Maximum
Any individual axle
34,000 lbs
Tandem Axle Maximum
Two consecutive axles spaced 40”-96” apart
Typical Weight Distribution: 5-Axle Semi
Steer Axle
12,000
Drive Tandems
34,000
Trailer Tandems
34,000
Maximum GVW: 80,000 lbs
Payload Math: How Much Can You Actually Haul?
Your payload capacity isn’t 80,000 lbs — it’s 80,000 minus the weight of everything that isn’t cargo.
Payload Calculation
Federal GVW limit 80,000 lbs
Tractor weight (typical day cab) -16,000 lbs
Sleeper berth add (if equipped) -2,000 lbs
Dry van trailer -14,000 lbs
Fuel (150 gal at 7 lbs/gal) -1,050 lbs
Driver + personal items -250 lbs
Available payload ~46,700 lbs
Payload by Equipment Type
| Configuration | Tare Weight | Payload |
|---|---|---|
| Day cab + dry van (53’) | ~30,000 lbs | ~50,000 lbs |
| Sleeper + dry van (53’) | ~33,000 lbs | ~47,000 lbs |
| Sleeper + reefer (53’) | ~36,000 lbs | ~44,000 lbs |
| Sleeper + flatbed (48’) | ~28,000 lbs | ~52,000 lbs |
| Sleeper + tanker | ~30,000 lbs | ~50,000 lbs |
The Bridge Formula (Federal Bridge Formula B)
Even if your total weight is under 80,000 lbs and each axle is within limits, you can still be overweight under the Bridge Formula. This formula limits weight based on the distance between axle groups.
W = 500 × [(LN / (N-1)) + 12N + 36]
W = Maximum weight (lbs) L = Distance between outer axles (feet) N = Number of axles in the group
Why this matters: The bridge formula prevents too much weight concentrated over too short a distance, which damages bridges. Even at 78,000 lbs GVW, you can violate the bridge formula if your axle spacing is wrong. Sliding tandems is how you fix bridge formula issues — move trailer tandems to redistribute weight across a longer wheelbase.
Common Bridge Formula Limits
| Axle Spacing (ft) | 2 Axles | 3 Axles | 4 Axles | 5 Axles |
|---|---|---|---|---|
| 4 | 34,000 | 34,000 | - | - |
| 8 | 38,000 | 42,000 | - | - |
| 20 | 46,000 | 51,000 | 56,500 | - |
| 30 | 51,000 | 54,500 | 60,500 | 66,000 |
| 40 | 56,000 | 58,500 | 64,500 | 70,000 |
| 51+ | - | - | - | 80,000 |
Sliding Tandems: Weight Distribution Tool
Sliding your trailer tandems is the primary method for redistributing weight between axle groups. Understanding this saves you from overweight fines.
←
Slide tandems forward (toward tractor)
Shifts weight OFF trailer tandems, ONTO drive tandems. Use when trailer tandems are overweight.
→
Slide tandems rearward (away from tractor)
Shifts weight OFF drive tandems, ONTO trailer tandems. Use when drive tandems are overweight.
Rule of thumb: Each hole (1 pin position, about 6 inches) shifts approximately 250-400 lbs between axle groups. If your drives are 1,000 lbs overweight, slide the trailer tandems back about 3-4 holes.
Critical reminder: Sliding tandems affects bridge formula calculations. Moving tandems too far back can create a bridge formula violation even if individual axle weights are legal. Always verify both axle weights AND bridge formula compliance after sliding.
Overweight Fines by Severity
Overweight fines vary by state, but they escalate quickly. Many states use a per-pound surcharge that makes heavy overweight extremely expensive.
| Overweight Amount | Typical Fine Range | Additional Consequences |
|---|---|---|
| 1-1,000 lbs over | $50-$200 | Warning in some states |
| 1,001-2,000 lbs | $150-$500 | Fine + possible re-route |
| 2,001-5,000 lbs | $300-$2,000 | Fine + must offload or get permit |
| 5,001-10,000 lbs | $1,000-$5,000 | OOS until corrected + CSA points |
| 10,001+ lbs | $2,500-$15,000+ | OOS + possible criminal charges + cargo impounded |
State Fine Extremes
Harshest States
- New York: Up to $22,500+ for extreme overweight
- Michigan: Per-axle fines, can exceed $10,000
- Georgia: $0.05-$0.10 per pound over, no cap
- California: Heavy fines + vehicle impound
More Lenient States
- Texas: Tolerances up to 5% on some roads
- Montana: Higher state road limits
- Several states: Warning first offense under 1,000 lbs
- Oversize/overweight permits: Available in all states
Weigh Station Strategies
1
Know Your Weight Before You Roll
Get a certified scale ticket (CAT scale) immediately after loading. Cost: $12-$15. Potential savings: thousands in fines. This is non-negotiable.
2
Use Bypass Programs
PrePass, Drivewyze, and similar programs use your safety record to bypass weigh stations. Clean records get bypassed 90%+ of the time. Saves time and reduces inspection exposure.
3
Keep BOL Accurate
Your Bill of Lading weight must match scale weight within tolerance. If the shipper underreported weight on the BOL, that’s their problem to fix — but you’ll be the one fined on the road. Verify at origin.
4
Manage Fuel Weight
Diesel weighs 7 lbs/gallon. Full tanks (300 gal) add 2,100 lbs. If you’re near max weight, plan fuel stops strategically — fuel up after the weigh station, not before.
Related: Complete Weigh Station Guide | Bill of Lading Guide
How Weight Affects Your Insurance
Direct Premium Impact
- Overweight violations go on your CSA Vehicle Maintenance BASIC
- CSA alerts trigger insurer reviews and premium increases
- Overweight-related accidents may void cargo coverage
- Repeat violations can make you uninsurable with standard carriers
Claims Complications
- Overweight at time of accident = potential coverage denial
- Cargo shifting claims — improper loading + overweight = liability
- Bridge/road damage — you’re liable for repair costs
- Third-party injury claims amplified when truck was overweight
Weight compliance is insurance compliance. Every overweight violation is a mark against your safety record that insurers see at renewal. Keep your loads legal, get scale tickets, and your premiums stay lower. Talk to agents who understand weight compliance →
Frequently Asked Questions
What happens if I’m overweight at a weigh station?
You’ll receive a fine based on how much you’re overweight and the state’s penalty schedule. For minor overweight (under 1,000 lbs), some states issue warnings. For significant overweight, you’ll be placed out of service until you offload enough cargo to reach legal weight — or obtain an oversize/overweight permit. The fine, re-routing, and offloading costs can easily exceed $1,000. The violation also hits your CSA scores for 24 months. See our Overweight Fines Guide for state-by-state details.
How do I know if I’m violating the bridge formula?
The bridge formula limits weight based on the distance between axle groups. Even if your total GVW is under 80,000 lbs and each axle is within individual limits, concentrated weight over a short wheelbase can violate the bridge formula. Use a bridge formula calculator app (like Axle Guru) or the FHWA bridge formula table. The simplest check: get weighed at a CAT scale — their printout shows individual axle weights you can check against bridge formula limits.
Can I get overweight permits?
Yes — every state issues oversize/overweight permits for loads that exceed standard limits. Permits are load-specific and route-specific, typically costing $15-$500 depending on the state and weight amount. Some loads require pilot cars and restricted travel hours. Apply through each state’s DOT website or use a permit service. Never try to move a known overweight load without a permit — the fines far exceed the permit cost.
Does being overweight affect my insurance coverage?
Potentially yes. If you’re involved in an accident while overweight, your insurer may argue you were operating outside policy terms. Overweight-related cargo damage claims face increased scrutiny. Additionally, overweight violations affect your CSA scores, which insurers review at every renewal. Multiple weight violations can increase premiums 10-25% or result in non-renewal. Learn about insurance audits.