Indiana truck weight limits
On Interstate highways in Indiana, federal weight limits apply. Four checks decide whether your truck is legal — and the one that surprises most drivers is the Federal Bridge Formula, which can fail a truck that passes every other limit.
Federal limits on Indiana Interstates
| Limit | Maximum | Applies to |
|---|---|---|
| Single axle | 20,000 lb | Any one axle |
| Tandem axle group | 34,000 lb | Axles 40–96 inches apart |
| Tridem axle group | governed by the bridge formula | 3 axles in a group (no flat federal cap) |
| Gross vehicle weight | 80,000 lb | The whole rig |
| Bridge formula | varies by spacing | Every group of 2+ axles |
The bridge formula check
L is the spacing in feet between the outer axles of a group, N the number of axles. A standard 5-axle rig at 51 ft is capped at 79,500 lb by this formula — under the 80,000 lb gross limit. Full explanation with worked examples.
Indiana-specific rules
Indiana is a Midwest freight funnel (I-65, I-70, I-80/90, I-69), and on its main system it tracks federal law closely: on the Interstate and on state-designated "heavy-duty highways," the limits are 20,000 lb single axle, 34,000 lb tandem, 80,000 lb gross, with the Federal Bridge Formula (Indiana adopted it as state law in 1975, IC 9-20-4). Where Indiana is different is its "grandfather law" on highways not designated heavy-duty: those roads keep pre-bridge-formula limits with a lower 73,280 lb gross cap. So the same rig can be legal at 80,000 lb on one route and capped at 73,280 lb one road over. Indiana also enforces an 800 lb per inch of tire width wheel-weight limit.
Indiana exceptions to the federal limits
Indiana runs two regimes depending on the road (IC 9-20-4, per the Indiana State Police size & weight summary):
| Group | Interstate / heavy-duty highways | Non-heavy-duty ("grandfather") highways |
|---|---|---|
| Single axle | 20,000 lb | up to 20,000 lb (rim-dependent) |
| Tandem axle group | 34,000 lb | up to 34,000 lb |
| Maximum gross | 80,000 lb (bridge formula) | 73,280 lb |
| Wheel weight | 800 lb per inch of tire width | 800 lb per inch of tire width |
- The grandfather law cuts both ways: on a short-wheelbase rig it can let a tandem keep 34,000 lb where the bridge formula would reduce it, but it caps the total at 73,280 lb on those non-heavy-duty roads.
- Two consecutive tandem sets may each carry 34,000 lb if the extreme axles are 36 ft or more apart.
- On Interstates, federal limits govern — 20,000 / 34,000 / 80,000 plus the bridge formula.
Seasonal & designated-route rules in Indiana
Indiana does not run a single statewide spring-thaw program, but counties and local authorities post seasonal ("frost") and embargo weight limits on specific local roads, and INDOT and locals post structurally limited routes and bridges year-round. These are local and route-specific — check for posted reduced-load and bridge limits on the county and city roads in your delivery leg, not just the state and Interstate system.
Overweight permits in Indiana
Loads over the legal limits need an oversize/overweight (OSOW) permit through Indiana DOR Motor Carrier Services / INDOT (single-trip or annual), route-specific by bridge and pavement rating. Some agricultural and certain-commodity moves carry statutory allowances — confirm your commodity and route before relying on one.
Fines & enforcement in Indiana
Enforced by the Indiana State Police (Commercial Vehicle Enforcement) at fixed scales and with portable/mobile enforcement. Overweight violations are penalised on a graduated per-pound-over basis; loads can be held until brought within limits.
What dispatchers should check in Indiana
- Heavy-duty vs. non-heavy-duty highway — this is the Indiana catch: on non-heavy-duty roads the grandfather law caps gross at 73,280 lb, not 80,000.
- Interstate — full federal 20,000 / 34,000 / 80,000 plus the bridge formula.
- Wheel weight — 800 lb per inch of tire width can govern a narrow-tire heavy load.
- Local postings — check county/city seasonal frost, embargo, and posted-bridge limits on the local-road portion of the route.
Indiana truck weight — frequently asked questions
How much can a truck weigh in Indiana?
On Indiana Interstates the federal gross-weight limit is 80,000 lb, with a 20,000 lb single-axle limit, a 34,000 lb tandem limit and the Federal Bridge Formula. Indiana sets its own limits on non-Interstate roads — see the Indiana-specific rules on this page.
Does Indiana follow federal truck weight limits?
On the Interstate system, yes — federal limits govern in every state. Off the Interstate, Indiana applies its own axle, gross and permit rules, detailed on this page where they have been verified against the official state source.
What is the single-axle weight limit in Indiana?
The federal single-axle limit of 20,000 lb applies on Indiana Interstates. Some states set a different single-axle figure on non-Interstate roads — check the Indiana-specific section above for the governing number.
What is the maximum tandem-axle weight in Indiana?
On Indiana Interstates the federal tandem limit is 34,000 lb. Several states allow a different tandem weight on non-Interstate roads — see the Indiana exceptions above for the figure that governs.
Scaled heavy in Indiana?
If the trailer tandems are over, the fix is usually a computed tandem slide, not unloading — see how sliding tandems shifts weight. And here's what an overweight ticket really costs before you decide to run it.
Run your scale-ticket weights through the federal and bridge-formula calculator in your browser. The full platform predicts axle loads from load placement before you load, computes the exact slide-to-legal fix, and applies Indiana rules on top of the federal baseline.
Open the free calculatorOur calculator runs the federal single, tandem, gross and Bridge Formula checks in seconds. The full platform adds per-state limits, axle-load prediction and the slide-to-legal fix.
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