From Sept 1 to May 31, if you’re running a commercial truck in Colorado’s mountains, you must carry chains. When the Colorado I-70 chain law for trucks is activated, you must use them. Enforcement is happening, fines are steep, and road closures cost everyone money.
What the law actually says
Season dates: From September 1 to May 31, commercial chain rules apply on Colorado’s designated mountain highways, including I-70.
Mandatory carry: Since August 7, 2024, all commercial vehicles over 16,000 lbs must carry chains or an approved traction device any time they’re on these roads during the season. It’s not limited to I-70 anymore.
When chains must be installed: If CDOT or CSP activates the Commercial Vehicle Chain Law, trucks must chain up to four drive tires. Approved traction devices like AutoSock may qualify, but requirements depend on axle configuration. Watch for highway signs and COtrip alerts.
Fines:
- $500 + $79 surcharge if you’re caught without chains.
- $1,000 + $157 surcharge if you block traffic.
- Local ordinances can be stricter: for example, Vail fines $1,500 for missing chains when required and $2,650 if a truck spins out without them.
Where Colorado I-70 chain law for trucks applies?
The rules aren’t just for I-70 anymore. Trucks must carry chains on all these corridors from September through May:
- I-70 west of Morrison (MP 259)
- CO-9 (Frisco–Fairplay)
- US-40 (Empire to Utah)
- US-50 (Salida to Utah)
- US-160 (Walsenburg to NM)
- US-285 (Morrison to NM)
- US-550 (entire route)
New left-lane restrictions also apply to CMVs in: Glenwood Canyon, Dowd Junction, west side of Vail Pass, both sides of Eisenhower/Johnson tunnels, Georgetown Hill, and Floyd Hill.
Enforcement is real
On Oct 1, 2025, CSP and Port-of-Entry officers ran a blitz near Dotsero:
- 468 trucks stopped
- 102 citations issued
- 50 of those for chain violations
Compliance is improving, but violations are still common. Troopers are making it clear—carry your chains or expect a ticket.
What you need to carry
- Chains or ATDs: Enough to cover four drive tires.
- Support gear: Headlamp, gloves, mat, and a set of “chain-up” coveralls to avoid wasting time when weather hits.
- Know your spots: Use designated chain-up areas, not the shoulder.
Driver checklist
- Check the forecast and COtrip before you enter the corridor. Colorado Department of Transportation
- Stage your chains where you can reach them fast.
- Practice once in the yard if you haven’t chained up since last season.
- Follow the left-lane rules in restricted areas. Colorado State Patrol
The mandatory carry rule now covers more highways, and fines are steep. For the industry, that means spending a bit more on chains and a few extra minutes chaining up, but fewer shutdowns and safer roads for everyone.
Carry your chains, follow the law, and keep the freight rolling.
