Utah Semitrailer Length Limit

Utah sits at the 48-foot federal floor in Appendix B. No grandfathered length above it — what you can actually run comes from Utah state law, which like most states is 53 feet.

Appendix B length48'0"

Federal floor48'0" (all states)

Kingpin conditionNone

Tractor + 2 units95' 129K

Tractor + 3 units95' 129K

This is a floor, not your length limit. Appendix B lists what a state was grandfathered to keep under the STAA of 1982 and must go on allowing on the National Network. It is not the state's own limit, and it is not permission to run that length on any road you like. Most states allow 53-foot semitrailers under their own law — that permission comes from state statute, not from this table — and every state can still restrict length on specific routes, in cities, and off the National Network. Use this to know the federal baseline, then check the state limit and the route.

01 The rule

What Utah has to allow

Nothing was grandfathered above the floor here, and that is not the same as a 48-foot limit. It means the federal table protects nothing beyond 48 feet in Utah; whatever Utah allows above it — 53 feet in most states — comes from Utah's own statute and can be changed by Utah.

The number comes from 23 CFR Part 658 Appendix B, the STAA grandfather list. It binds Utah on the National Network and cannot be lowered. It says nothing about what Utah allows beyond it, which is where state law takes over.

02 The details

Length, kingpin and combinations

Appendix B semitrailer length: 48'0" (the federal floor)
Kingpin-to-rear-axle condition: None in Appendix B for this state.
Tractor plus two trailing units: 95 feet at up to 129,000 lb
Tractor plus three trailing units: 95 feet at up to 129,000 lb
Other grandfathered combinations: State submission includes multiple vehicles in this category—see individual State listings.
Past the legal length: a Utah oversize permit — see Utah oversize permits.

Utah Trailer Length FAQ

What is the legal trailer length in Utah without a permit?

The federally protected length on the National Network is 48'0" (23 CFR 658 Appendix B). That is the 48-foot floor every state must allow. Utah state law sets what you can actually run, and for most states that is 53 feet.

Can I run a 53-foot trailer in Utah?

Appendix B only protects 48'0" in Utah. 53-foot trailers are common there under Utah state law, but that permission is state statute, not this federal table — confirm the current Utah limit and any route restriction.

Are doubles or triples allowed in Utah?

Utah holds grandfathered longer-combination-vehicle rights under Appendix C. Tractor plus two trailing units: 95 feet at up to 129,000 lb. Tractor plus three: 95 feet at up to 129,000 lb.

Does this length apply on every road in Utah?

No. Appendix B binds the National Network — the Interstates plus the designated primary routes. Off the network, and inside cities, Utah can and does restrict length, and posted route restrictions still apply. Check the route as well as the number.

Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: eCFR, 23 CFR 658 Appendix B and C (title 23 as of 2026-07-23). See our Terms & Disclaimer.

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Utah Semitrailer Length Limit

What Utah has to allow

Length, kingpin and combinations

Utah Trailer Length FAQ

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Utah Oversize Permits

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