Tennessee truck weight limits
On Interstate highways in Tennessee, 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 Tennessee 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.
Tennessee-specific rules
Tennessee is a Southeast freight hub (I-40, I-24, I-75, I-81, plus the Memphis and Nashville distribution corridors) and it tracks the federal limits closely: on the Interstate and on state highways the operative limits are 20,000 lb single axle, 34,000 lb tandem, 80,000 lb gross, with the Federal Bridge Formula (T.C.A. § 55-7-203). The statute carries an older grandfather baseline (18,000 lb single / 32,000 lb tandem / 73,280 lb gross) that is raised to the federal numbers once the bridge formula is applied, so for a normal rig the numbers you plan to are the standard 20k/34k/80k. Where Tennessee bites is terrain — TDOT posts truck-route restrictions on steep mountain grades and specific routes.
Tennessee exceptions to the federal limits
Tennessee's operative limits (T.C.A. § 55-7-203):
| Group | Limit |
|---|---|
| Single axle | 20,000 lb |
| Tandem axle group | 34,000 lb |
| Maximum gross | 80,000 lb (Federal Bridge Formula) |
- The statute's grandfather baseline (18,000 lb single / 32,000 lb tandem / 73,280 lb gross) is the floor; applying the bridge formula raises a qualifying vehicle to the 20,000 / 34,000 / 80,000 figures above.
- Two consecutive tandem sets may each carry 34,000 lb where spacing allows.
- On Interstates, federal limits govern — the same 20,000 / 34,000 / 80,000 plus the bridge formula.
Seasonal & designated-route rules in Tennessee
Tennessee does not run a statewide spring "frost law" program. The restrictions that matter here are TDOT truck-route restrictions and posted-bridge limits — Tennessee's mountainous east has steep grades and structurally limited routes where through-truck travel is restricted or re-routed. Check TDOT's current route restrictions and posted-bridge signage before committing a heavy or long load, especially on secondary and mountain routes.
Overweight permits in Tennessee
Loads over the legal limits need an oversize/overweight permit from TDOT (single-trip or annual), route-specific by bridge and pavement rating. Mountain and posted-bridge routes may be excluded regardless of permit.
Fines & enforcement in Tennessee
Enforced by the Tennessee Highway Patrol / Department of Safety 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 Tennessee
- Plan to the federal numbers — 20,000 single / 34,000 tandem / 80,000 gross plus the bridge formula, on Interstates and state highways alike.
- Terrain & route restrictions — check TDOT truck-route restrictions on steep/mountain routes in East Tennessee before routing a heavy load.
- Posted bridges — obey signed bridge weight limits; a permit doesn't override them.
Tennessee truck weight — frequently asked questions
How much can a truck weigh in Tennessee?
On Tennessee 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. Tennessee sets its own limits on non-Interstate roads — see the Tennessee-specific rules on this page.
Does Tennessee follow federal truck weight limits?
On the Interstate system, yes — federal limits govern in every state. Off the Interstate, Tennessee 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 Tennessee?
The federal single-axle limit of 20,000 lb applies on Tennessee Interstates. Some states set a different single-axle figure on non-Interstate roads — check the Tennessee-specific section above for the governing number.
What is the maximum tandem-axle weight in Tennessee?
On Tennessee Interstates the federal tandem limit is 34,000 lb. Several states allow a different tandem weight on non-Interstate roads — see the Tennessee exceptions above for the figure that governs.
Scaled heavy in Tennessee?
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 Tennessee 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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