Truck Weight and Size Limits

Understanding Truck Weight and Size Limits

Weight and size regulations govern how heavy and large commercial trucks can be on U.S. highways. These limits exist to protect road infrastructure, ensure safety, and maintain traffic flow. For dispatchers, understanding these limits is critical—violating them results in expensive fines, out-of-service orders, and potential infrastructure damage liability.

Why Weight and Size Limits Exist

Infrastructure Protection:

Roads and Bridges:

Designed for maximum weight capacities
Overweight trucks cause:
- Pavement damage and cracking
- Bridge structural stress
- Shortened infrastructure lifespan
- Taxpayer costs for repairs

The Math:

Damage increases exponentially with weight
A truck 10% overweight causes 40% more damage than legal weight
Heavy trucks cause 95% of highway wear despite being only 10% of traffic

Safety:

Handling and Braking:

Overweight trucks have:
- Longer stopping distances
- Reduced maneuverability
- Increased rollover risk
- Brake system overload

Accident Severity:

Heavier trucks cause more severe crashes
Greater damage to other vehicles
Higher fatality rates

Fair Competition:

Level Playing Field:

Weight limits ensure carriers compete fairly
Prevents unsafe overloading to haul more cargo
Protects carriers who comply with limits

Federal Weight Limits

Gross Vehicle Weight (GVW):

Maximum:

80,000 lbs - Federal limit on Interstate highways
Applies to Gross Combination Weight Rating (GCWR) for tractor-trailer

Components:

Tractor weight
Trailer weight
Cargo weight
Fuel weight
Total of all combined

Axle Weight Limits:

Single Axle:

20,000 lbs maximum

Tandem Axle (Two Axles):

34,000 lbs maximum
Spacing must be 40-96 inches apart

Example Standard Configuration:

Steer axle (single): 12,000 lbs
Drive axles (tandem): 34,000 lbs
Trailer axles (tandem): 34,000 lbs
Total: 12,000 + 34,000 + 34,000 = 80,000 lbs

Bridge Formula:

Purpose:

Distributes weight over more axles
Protects bridges from concentrated loads
More axles = Can carry more weight

Bridge Formula B:

W = 500 × [(LN / (N-1)) + 12N + 36]

Where:

W = Maximum weight in pounds
L = Distance in feet between outer axles of group
N = Number of axles in group

Simplified:

Longer wheelbase + more axles = Can carry more weight
Formula ensures weight spread over sufficient distance

Example:

5-axle truck with 51-foot wheelbase = 80,000 lbs max (standard)
Same truck with shorter wheelbase might be limited to 75,000 lbs

State Weight Limits

Variations by State:

Most States:

Follow federal 80,000 lb limit on Interstate highways
May have different limits on state highways

Higher Limits (Special Permits):

Michigan:

Up to 164,000 lbs on certain roads
Requires 11-axle configuration
Special industry exemption (automotive manufacturing)

Maine:

Up to 100,000 lbs on designated roads
Must have 6+ axles
Forestry industry exception

North Dakota, South Dakota:

Up to 105,500 lbs on certain highways
Agricultural hauling

Lower Limits:

California:

80,000 lbs federal limit applies
But Bridge Formula strictly enforced
Some state roads have lower limits (70K, 60K)
CalTrans enforcement aggressive

Local Roads:

Counties and cities can set lower limits
Posted weight limit signs
"No Trucks Over X Tons"

Size Limits (Dimensions)

Width:

Federal Standard:

102 inches (8.5 feet) maximum
Applies to Interstate highways

State Variations:

Most states allow 102 inches
Some allow up to 8'6" on certain roads
Oversize permits for wider loads

Height:

Federal Standard:

No federal maximum height limit
Varies by state

Common State Limits:

13 feet 6 inches (13'6") - Most common
14 feet - Some states
Clearances vary - Bridges, overpasses, tunnels

Dispatcher Critical:

ALWAYS verify route clearances for tall loads
Low bridges cause severe accidents
Bridge strikes = $50,000-$500,000 damage + liability

Resources:

State DOT websites list bridge clearances
Trucking GPS shows clearances on route
National Bridge Inventory database

Length:

Trailer Length:

53 feet - Most common maximum
48 feet - Older standard (still common)

Overall Length:

Varies by state
Typically 65-75 feet total (tractor + trailer)

Kingpin to Rear Axle:

41 feet maximum in most states
Prevents tail swing issues

Front Overhang:

3 feet maximum beyond front axle

Weigh Stations and Enforcement

Weigh Stations:

Purpose:

Verify trucks are within legal weight limits
Check for safety violations
Enforce permits and registration

Who Must Stop:

All commercial vehicles meeting certain criteria:
- Gross weight 10,001+ lbs, OR
- GVWR 10,001+ lbs, OR
- As posted (varies by state)

Bypass Programs:

PrePass - Transponder system
Bestpass - Toll and weigh station bypass
If truck is compliant and has good safety record, green light = bypass

Weigh Station Process:

1. Enter Scale:

Pull onto scale when directed
Vehicle weighed (all axles simultaneously on modern scales)

2. Inspection (If Selected):

Random or targeted inspections
Level 1: Full inspection (37-step, driver + vehicle)
Level 2: Walk-around (driver + vehicle exterior)
Level 3: Driver only (credentials, logbook)

3. If Overweight:

Ticket issued - Fine varies by amount over
Out-of-service until weight reduced
Must offload cargo or redistribute

Weight Enforcement:

Mobile Scales:

Law enforcement can use portable scales
Roadside inspections
Targeted enforcement

Fines:

Slightly Over (1,000-2,000 lbs):

$100-$500 fine

Moderately Over (2,000-5,000 lbs):

$500-$1,500 fine
Possible out-of-service

Significantly Over (5,000+ lbs):

$1,000-$10,000+ fine
Out-of-service until corrected
CSA points
Possible criminal charges

Per-Axle Violations:

Fined for each axle over limit
Can add up quickly

Calculating Load Weight

Before Loading:

Know Your Weights:

1. Tractor (Empty) Weight:

Typically 15,000-18,000 lbs
Varies by model, fuel, equipment

2. Trailer (Empty) Weight:

Dry van: ~13,000-15,000 lbs
Reefer: ~15,000-17,000 lbs (heavier due to reefer unit)
Flatbed: ~10,000-12,000 lbs (lighter, no walls/roof)

3. Fuel:

Diesel weighs ~7 lbs per gallon
Full tanks (200-300 gallons) = 1,400-2,100 lbs

4. Available Cargo Capacity:

80,000 lbs (max)
Minus tractor (~17,000 lbs)
Minus trailer (~14,000 lbs for dry van)
Minus fuel (~1,500 lbs)
= ~47,500 lbs available for cargo

Load Planning:

Example Calculation:

Given:

Tractor: 17,000 lbs
Dry van trailer: 14,000 lbs
Fuel: 1,500 lbs (half tanks)
Total: 32,500 lbs before cargo

Cargo Limit:

80,000 lbs (max) - 32,500 lbs (equipment) = 47,500 lbs cargo max

Shipper Says:

"We have 25 pallets, 2,000 lbs each"
25 × 2,000 = 50,000 lbs

Problem:

50,000 lbs cargo + 32,500 lbs equipment = 82,500 lbs total
2,500 lbs overweight!

Solution:

Reduce cargo to 23 pallets (46,000 lbs)
OR partially fuel (reduce fuel weight)
OR use lighter trailer (flatbed)

Weight Distribution:

Axle Limits:

Even if under 80,000 lbs total, individual axles can't exceed:
- Steer: 12,000-14,000 lbs (varies by state)
- Drive tandem: 34,000 lbs
- Trailer tandem: 34,000 lbs

Common Issue:

Load positioned too far forward = drive axles overweight
Load positioned too far back = trailer axles overweight
Solution: Slide trailer tandems to redistribute weight

Tandem Sliding:

Trailer axles can slide forward/back
Adjusts weight distribution
Driver responsibility to check and adjust

Overweight and Oversize Permits

When Needed:

Overweight:

Load exceeds 80,000 lbs but is non-divisible
Non-divisible = Cannot be broken into smaller loads without damage
Examples: Heavy machinery, transformers, generators

Oversize:

Exceeds width (8.5'), height (13'6"), or length limits

Permit Process:

Application:

Per state - Need permit for every state on route
Provide load specs (weight, dimensions)
Provide route
Provide travel dates

Costs:

Overweight: $15-$150 per state
Oversize: $50-$500+ per state depending on size
Pilot cars: $150-$300/day if required
Law enforcement escort: $75-$200/hour if required

Processing Time:

Standard: 5-10 business days
Expedited: 24-48 hours (extra fee)

Routing:

Must follow exact permitted route
Cannot deviate even for fuel or food
Deviations = Violation

(Detailed coverage in Permits article)

Consequences of Weight Violations

Immediate:

Fines:

$100-$10,000+ depending on amount overweight
Compounding fines (per axle violations)

Out-of-Service:

Cannot move truck until weight corrected
Must offload cargo at current location
Arrange for another truck to pick up excess
Costly delays

Long-Term:

CSA Points:

Weight violations add CSA points
Affects safety rating
Increases inspection frequency

Insurance:

Rate increases for poor safety record
Coverage denial for chronic violators

Shipper Relationships:

Lost customers who won't tolerate violations
Damage to reputation

Infrastructure Damage:

Liable for road/bridge damage if caught significantly overweight
Can be billed for repairs ($10,000-$500,000+)

Criminal Charges:

Extreme Violations:

Grossly overweight (20,000+ lbs over)
Repeat offenders
Fraudulent permits

Penalties:

Fines $10,000+
Jail time possible
Authority revocation

Dispatcher's Weight Management Responsibilities

Before Accepting Load:

1. Verify Load Weight:

✅ Ask shipper exact weight of cargo
✅ Don't accept "approximately" - need precise weight
✅ Add 10% safety margin to shipper estimate (often low)

2. Calculate Total Weight:

✅ Tractor weight + Trailer weight + Fuel + Cargo
✅ Verify under 80,000 lbs
✅ Check individual axle limits

3. Verify Route:

✅ Interstate = 80,000 lbs usually OK
✅ State/local roads = Check for lower posted limits
✅ Bridges = Verify weight ratings

4. If Overweight:

✅ Refuse load, OR
✅ Obtain overweight permit (if non-divisible), OR
✅ Reduce cargo to legal limit

Driver Communication:

Before Loading:

✅ "Shipper says 45,000 lbs, verify on scale ticket after loading"
✅ "If over 80K, do NOT leave - call me immediately"
✅ "Slide tandems to distribute weight properly"

After Loading:

✅ "Send me scale ticket photo showing exact weight"
✅ "Verify all axles within limits"
✅ "If overweight, talk to shipper about removing cargo"

Documentation:

Keep Records:

✅ Scale tickets from loading
✅ Bill of Lading with stated weight
✅ Shipper certification of weight (if available)

Defense:

If stopped and overweight, show you relied on shipper's stated weight
Doesn't eliminate fine, but shows good faith effort
May reduce penalty

Special Considerations

Reefer Units:

Weight Impact:

Refrigeration unit adds ~2,000-2,500 lbs vs. dry van
Reduces available cargo capacity
Must factor into calculations

Fuel:

Reefer fuel adds weight (separate tank, 30-50 gallons)

Liquid Loads:

Sloshing:

Liquid cargo shifts during braking/turning
Affects vehicle stability
Requires experience and caution

Weight Calculation:

Water: 8.34 lbs/gallon
Milk: 8.6 lbs/gallon
Fuel: 7 lbs/gallon
Chemicals: Varies (check density)

Palletized Freight:

Pallet Weight:

Standard wood pallet: 30-50 lbs each
Must add to cargo weight calculation

Example:

24 pallets × 2,000 lbs each = 48,000 lbs cargo
24 pallets × 40 lbs each = 960 lbs pallets
Total: 48,960 lbs (not 48,000!)

Weight Distribution Best Practices

Proper Loading:

Weight Placement:

Heavier items on bottom, lighter on top
Even distribution left to right
Proper fore-aft placement for axle balance

Tandem Positioning:

Slide trailer tandems to balance axle weights
Too much on drives? Slide tandems back
Too much on trailer? Slide tandems forward

Verification:

CAT Scale:

Certified scales at truck stops
Cost: $12-$15 per weigh
Provides individual axle weights
Legal documentation of weight

Process:

Pull onto scale (all axles on scale)
Get printout showing:
- Steer axle weight
- Drive axle weight
- Trailer axle weight
- Gross weight
Verify all within limits
Adjust if needed
Reweigh (free within 24 hours)

Conclusion

Weight and size limits are fundamental to safe, legal trucking operations. Understanding and respecting these limits protects infrastructure, ensures safety, and keeps carriers compliant.

Key Takeaways:

Federal Limits:

✅ 80,000 lbs maximum GVW on Interstate highways
✅ 20,000 lbs single axle max
✅ 34,000 lbs tandem axle max
✅ 102 inches (8.5') width
✅ 13'6" height (varies by state)
✅ 53' trailer length (most common)

Dispatcher Must:

✅ Calculate total weight before accepting load
✅ Verify cargo weight with shipper
✅ Factor in tractor, trailer, fuel weights
✅ Never dispatch knowingly overweight truck
✅ Obtain permits for legal overweight loads
✅ Document weight with scale tickets

Violations:

Fines: $100-$10,000+ depending on severity
Out-of-service: Until weight corrected
CSA points: Affect safety rating
Liability: For infrastructure damage

Prevention:

✅ Know your equipment weights
✅ Verify cargo weights accurately
✅ Use CAT scales after loading
✅ Slide tandems to distribute weight
✅ Plan routes considering weight limits

"An ounce of prevention is worth a pound of fines. Always verify weight before rolling."

Continue Learning:

Master weight and size limits to operate safely and legally. Continue your education at Carriversity.