The load
Both inputs are in the address bar, so this result is a link you can send. There is no script on this page.
Common wheelbases
12 of 13 tested
10,000 lb over 100 ft of outer wheelbase, every axle count from 2 to 13.
Clears · 0 lb left on the binding group, axles 1–2
Open this rig in the axle weight checkerClears · 0 lb left on the binding group, axles 1–10
Open this rig in the axle weight checkerClears · 0 lb left on the binding group, axles 1–11
Open this rig in the axle weight checkerClears · 0 lb left on the binding group, axles 1–12
Open this rig in the axle weight checkerClears · 0 lb left on the binding group, axles 1–13
Open this rig in the axle weight checkerWhat this answers, and where the answer stops
It is a feasibility probe on federal geometry, not a specification for a truck.
Every axle count from 2 to 13 against 23 U.S.C. §127(a) — each candidate's full set of consecutive-axle groups, the 20,000 lb single-axle limit, the 34,000 lb tandem cap and the 34-34-at-36-ft exception.
Whether a tractor can be built that puts axles where the model puts them; any state’s own axle or gross limits; permit fees; escorts; and seasonal restrictions. A configuration that clears here can still be illegal in a specific state on a specific road in March.
Nothing, no account, and no JavaScript. Both inputs are in the query string and the whole page is server-rendered, so it works with scripting disabled and the result is a shareable link.
Three steps, in order
One candidate per axle count
For each axle count the solver builds the evenly spaced, evenly loaded layout over the outer wheelbase you gave it, with the rounding residue landing on the last axle so the gross stays exactly the number you typed.
Every group of every candidate gets checked
The same engine the axle weight checker uses, so a candidate here and the same rig there cannot disagree. Each candidate reports the group with the least headroom, because that is the group that decides.
Ranked, fewest axles first
Passing configurations come first, cheapest rig first; the rest are ranked by how close they came. The fewest-axle pass is marked recommended with an outline, and each row links into the forward tool with that layout preloaded.
Two things that make the answer trustworthy
A "no" here is a real no
The modelled layout is the optimum for a fixed weight, length and axle count: even spacing gives every group the longest span it can have, even loading gives every group the lightest weight it can have, and the per-axle limit is minimised in its maximum at the same time. So the even layout maximises the slack on whichever constraint binds.
That is what makes a failure conclusive rather than suggestive. If 13 axles over that wheelbase cannot carry the load, no arrangement of 13 axles can — the fix is more outer wheelbase, not more axles. The invariant is asserted against randomised perturbations in the test suite rather than taken on trust.
- Axle counts tested
- 2–13
- Candidates evaluated
- 13
- Clearing the formula
- 12
The result is a link
Both inputs live in the query string, so a configured result can be bookmarked, sent to a carrier and reopened unchanged. The length presets are anchors rather than buttons for exactly that reason.
And every candidate carries a link into the axle weight checker with its own layout already encoded, so the step from "this many axles would work" to "is my actual rig legal in Ohio" is one click and no retyping.
- Federal single axle
- 20,000 lb
- Federal tandem axle
- 34,000 lb
- Federal gross weight
- 80,000 lb
Questions
Does this tell me which truck to buy?
No. It reports the minimum number of axles the federal bridge formula requires for that weight across that outer wheelbase, using an evenly spaced, evenly loaded layout. Real tractors cannot put axles at arbitrary positions, so each row links into the axle weight checker with the layout preloaded — edit it to the rig you actually have and re-check.
Why is "no configuration passes" a reliable answer?
Because the modelled layout is the best case. For a fixed weight, length and axle count, even spacing gives every axle group the longest span it can have and even loading gives every group the lightest weight it can have, so it maximises the slack on whichever constraint binds. If the even layout fails at N axles, no arrangement of N axles over that length passes — the load needs more outer wheelbase, not more axles.
What about the 34-34 tandem exception?
It is the one geometry even spacing cannot reach, so it is evaluated separately. 23 U.S.C. §127(a)(3) lets two consecutive tandem sets each carry 34,000 lb when their outer axles are at least 36 ft apart — 68,000 lb where the bare formula allows only 66,000 — so at four axles the solver tests the two-tandem arrangement as well and keeps whichever clears.
Does a passing configuration mean no permit?
Only below 80,000 lb. The bridge formula governs how weight is distributed; 23 U.S.C. §127(a) separately caps an unpermitted Interstate vehicle at 80,000 lb gross. Above that every configuration here needs an overweight permit, and the axle weight checker prices it against the issuing state’s own published schedule.