Colorado Semitrailer Length Limit

Colorado is grandfathered at 57'4". Every state must allow 48 feet on the National Network; Colorado kept the right to allow 57'4" and cannot drop below it.

Appendix B length57'4"

Federal floor48'0" (all states)

Kingpin conditionNone

Tractor + 2 units111' 110K

Tractor + 3 units115.5' 110K

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 Colorado has to allow

Colorado kept 57'4" under the STAA grandfather, so anything up to that length is federally protected on the National Network and Colorado cannot legislate below it. A standard 53-foot van sits comfortably inside it.

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

02 The details

Length, kingpin and combinations

Appendix B semitrailer length: 57'4"
Kingpin-to-rear-axle condition: None in Appendix B for this state.
Tractor plus two trailing units: 111 feet at up to 110,000 lb
Tractor plus three trailing units: 115.5 feet at up to 110,000 lb
Other grandfathered combinations: 78 feet
Past the legal length: a Colorado oversize permit — see Colorado oversize permits.

Colorado Trailer Length FAQ

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

The federally protected length on the National Network is 57'4" (23 CFR 658 Appendix B). Colorado was grandfathered above the 48-foot floor and must keep allowing it.

Can I run a 53-foot trailer in Colorado?

Yes. Colorado is grandfathered at 57'4", so 53 feet is inside the federally protected length on the National Network.

Are doubles or triples allowed in Colorado?

Colorado holds grandfathered longer-combination-vehicle rights under Appendix C. Tractor plus two trailing units: 111 feet at up to 110,000 lb. Tractor plus three: 115.5 feet at up to 110,000 lb.

Does this length apply on every road in Colorado?

No. Appendix B binds the National Network — the Interstates plus the designated primary routes. Off the network, and inside cities, Colorado 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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Colorado Semitrailer Length Limit

What Colorado has to allow

Length, kingpin and combinations

Colorado Trailer Length FAQ

More for Colorado

Colorado Weight Limits

Colorado Oversize Permits

Colorado 511

All States

Check Colorado before you roll