California’s bridge law chart, set out in Vehicle Code Section 35551, caps the weight that any group of two or more consecutive axles can place on a highway based on how many axles are in the group and the distance between the outermost ones. The overall ceiling for most commercial vehicles is 80,000 pounds gross vehicle weight. Below that cap, the specific limits come straight from the table.
The California Bridge Law Chart
The table below shows the maximum weight in pounds allowed on a group of consecutive axles at a given outer-to-outer distance in feet. It covers groups of two through six axles at distances from 4 feet through 51 feet and beyond.1California Legislative Information. California Vehicle Code 35551 – Axle Limits
| Distance (ft) | 2 Axles | 3 Axles | 4 Axles | 5 Axles | 6 Axles |
|---|---|---|---|---|---|
| 4 | 34,000 | 34,000 | 34,000 | 34,000 | 34,000 |
| 8 | 34,000 | 34,000 | 34,000 | 34,000 | 34,000 |
| 10 | 40,000 | 43,500 | 43,500 | 43,500 | 43,500 |
| 15 | 40,000 | 47,000 | 52,000 | 52,000 | 52,000 |
| 20 | 40,000 | 51,000 | 55,500 | 55,500 | 55,500 |
| 25 | 40,000 | 54,500 | 58,500 | 58,500 | 58,500 |
| 30 | 40,000 | 58,500 | 62,000 | 62,000 | 62,000 |
| 35 | 40,000 | 60,000 | 65,500 | 65,500 | 65,500 |
| 40 | 40,000 | 60,000 | 68,500 | 70,000 | 70,000 |
| 45 | 40,000 | 60,000 | 72,000 | 76,000 | 80,000 |
| 50 | 40,000 | 60,000 | 75,500 | 79,000 | 80,000 |
| 51+ | 40,000 | 60,000 | 76,000+ | 80,000 | 80,000 |
How to Read the Chart
The underlying principle is simple. More axles and greater spacing between them allow more total weight, because the load spreads across a longer stretch of road and bridge deck. Two axles sitting close together concentrate stress on a short span, so the limit stays low. Add a third axle or push the outer axles farther apart, and the ceiling climbs.
A few reference points are worth memorizing. Any group of two or more consecutive axles spaced between 4 and 8 feet apart tops out at 34,000 pounds no matter how many axles are in the group. That is the number most tandem configurations hit, and it is why 34,000 shows up again and again in weight enforcement.
Two-axle groups cap at 40,000 pounds once the spacing exceeds 8 feet, and nothing more is gained from pushing them farther apart. Three-axle groups max out at 60,000 pounds at 32 feet and beyond. Five-axle groups reach the 80,000-pound gross vehicle weight ceiling at 51 feet of spacing. Six-axle groups get there at just 45 feet, because the extra axle spreads the same load more effectively.1California Legislative Information. California Vehicle Code 35551 – Axle Limits
The chart comes from the Federal Bridge Formula, which the Federal Highway Administration uses to protect bridge decks and pavement from concentrated loads. The formula takes three inputs: the number of axles in a group, the outer-to-outer distance in feet, and the resulting maximum weight rounded to the nearest 500 pounds.2Federal Highway Administration. Bridge Formula Weights California publishes the output as the Section 35551 table so drivers do not have to run the math.
Single Axle and Per-Wheel Caps
The group chart is not the only limit. Vehicle Code Section 35550 sets independent fixed ceilings: no single axle can place more than 20,000 pounds on the highway, and no single wheel or set of wheels on one end of an axle can exceed 10,500 pounds.3California Legislative Information. California Code VEH 35550 – Axle Limits
These caps apply alongside the group table, not instead of it. A legal load has to clear both the group limit for its spacing and the per-axle and per-wheel limits at the same time. The lowest applicable number wins.
Trailer Combinations Use a Different Table
Vehicle combinations with a trailer or semitrailer fall under Section 35551.5 instead of the main 35551 table, and the numbers are tighter. The single-axle cap drops to 18,000 pounds and the per-wheel limit drops to 9,500 pounds. The front steering axle of the tractor is the one exception, allowed up to 12,500 pounds.4Caltrans. Caltrans – Weight Limitation
Section 35551.5 also has its own group axle table, with a lower overall cap of 76,800 pounds at distances of 56 feet or more.5California Legislative Information. California Code VEH – Axle Limits A five-axle tractor-semitrailer uses this chart, not the more generous one above. That mix-up catches carriers out.
Weight Bonuses That Modify the Chart
Two allowances let a qualifying vehicle exceed the standard numbers.
Under Vehicle Code Section 35559, the power unit of a near-zero or zero-emission truck can exceed the normal gross weight limits by up to 2,000 pounds, raising the maximum possible gross vehicle weight to 82,000 pounds. If a combination has more than one power unit, the 2,000-pound allowance can be split between them but cannot exceed 2,000 pounds total.5California Legislative Information. California Code VEH – Axle Limits The federal government grants a parallel 2,000-pound allowance under 23 U.S.C. 127(s) for natural gas and electric trucks on the Interstate system.6Alternative Fuels Data Center. Natural Gas Vehicle (NGV) and Electric Vehicle (EV) Weight Exemption The allowance exists because battery packs and natural gas systems are heavier than comparable diesel components.
Trucks fitted with an auxiliary power unit or other idle reduction technology get up to 550 pounds on top of gross, single axle, tandem axle, and bridge formula limits under federal law. The driver has to carry proof of the APU’s weight and show the unit works if an officer asks.7Alternative Fuels Data Center. Idle Reduction and Alternative Fuel Vehicle Weight Exemption
When You Need an Overweight Permit
Loads that cannot fit under the chart require a special transportation permit from Caltrans before they move. Permits are only available for loads that are reasonably non-divisible, meaning the cargo would lose value or function if broken into smaller pieces.8Caltrans. General Provisions Relating to Oversize/Overweight Transportation Permits Convenience or cost savings from running one truck instead of two will not qualify.
Caltrans issues single-trip permits for a specific load on a specific route and annual permits for repeated movements within defined parameters, though annual permits are blocked from certain restricted routes.9Caltrans. Transportation Permits (Oversize/Overweight Vehicles)
What an Overweight Violation Costs
Fines under Vehicle Code Section 42030 scale with how far over the limit the vehicle weighs:
- 1 to 1,000 lbs over: $20 base fine
- 1,001 to 1,500 lbs: $30
- 1,501 to 2,000 lbs: $40
- 2,001 to 2,500 lbs: $55
- 2,501 to 3,000 lbs: $85
- 3,001 to 3,500 lbs: $105
- 3,501 to 4,000 lbs: $125
- 4,001 to 4,500 lbs: $145
- 4,501 to 5,000 lbs: $175
- 5,001 to 6,000 lbs: $0.04 per pound over the limit
- 6,001 to 7,000 lbs: $0.06 per pound
- 7,001 to 8,000 lbs: $0.08 per pound
- 8,001 to 10,000 lbs: $0.15 per pound
- 10,001 lbs and over: $0.20 per pound
Those are base fines. Court penalty assessments and surcharges can multiply the actual out-of-pocket amount several times over. Any violation involving excess weight above 4,500 pounds is charged as a misdemeanor rather than an infraction, which can carry county jail time on top of the fine.
Violating the terms of an overweight permit is its own offense, with a fine of up to $500, potential jail time of up to six months, and an additional per-pound fine calculated under the same schedule for weight above what the permit authorized.[mfm]California Legislative Information. California Vehicle Code 35784 – Penalties[/mfn] An overweight stop also means delay while cargo is offloaded to legal weight at the scene, and repeat violations accumulate compliance points that can affect future permit eligibility.