Colorado CDL drivers face a problem few other states throw at them: a chain law that can change the day you drive. When snow hits a mountain pass, a truck that is legal at the bottom of the hill may be illegal at the top. This guide explains how the chain law works, where it applies, and what else a Colorado CDL holder needs to keep current.
Which Colorado highways have a commercial chain law?
The Colorado State Patrol lists the roads where the commercial chain law applies. They include I-70 west of Morrison, Highway 9 between Frisco and Fairplay, US 50 west of Salida, US 160 west of Walsenburg, US 285 and all of US 550. I-70 is the corridor most truckers know, since it crosses the Continental Divide and runs through the Eisenhower-Johnson tunnels.
Colorado's commercial chain law applies to commercial vehicles over about 16,000 pounds and runs during the winter season, September 1 through May 31 on the designated highways. Carriers still have to chain up whenever the posted conditions call for it.
The state's own sources do not agree on every detail. An older CDOT tips sheet describes a narrower carry requirement, while the State Patrol page lists the wider set of roads above. Treat the State Patrol list as a starting point and check current CDOT information before a winter run. If your route uses a pass you have never driven, read about it first and ask other drivers what the grades are like.
How many chains does a Colorado truck need?
The State Patrol explains chain requirements by drive-tire count:
- A straight truck with four drive tires needs chains on four tires.
- A bus with two drive tires needs two chains.
Combination vehicles have their own configurations, so read the full State Patrol chain page for your rig. Do not guess at a chain setup on the shoulder with traffic going by.
How do Colorado drivers find out when chains are required?
CDOT announces chain requirements through several channels: variable message signs, the 511 phone line, cotrip.org and text alerts. Sign up before the season starts, since the fastest way to get stuck is to find out at the sign.
Put the 511 number and cotrip.org on your phone's home screen. Check them before you leave and again at your last stop before the climb.
What Colorado CDL paperwork can trip up a mountain driver?
- A DOT medical exam is needed at least every two years, and providers report to the FMCSA National Registry within 24 business hours.
- Without a current DOT medical card a Colorado CDL holder must downgrade to a regular license.
- CLP written test results are valid for only one CLP issuance. If you add a class or endorsement after getting a CLP, you must retake all the knowledge tests and get a new permit.
That last point catches students who change plans mid-course. Decide on your class and endorsements before you test.
Can you transfer an out-of-state CDL to Colorado?
Colorado lets out-of-state CDLs that expired less than one year earlier transfer with the written and skills tests waived. Out-of-state CLPs do not transfer, so plan on a Colorado permit of your own if you arrive with only one.
What Colorado permit and test basics apply before you climb?
- A Colorado CLP is valid for one year with no renewal.
- Hold the CLP for 14 calendar days before the skills test.
- If you fail any portion of the skills test, you retest on another day and repeat all three portions.
How should you drive a mountain grade?
Mountain skill is part of every CDL knowledge test, because the federal manual covers it. Pick a lower gear before you start down, since you want the engine holding the truck back instead of the brakes. A common rule in the manual is that the gear you would use to climb a grade is the one to use going down it. Brakes that overheat on a long descent can fade, and runaway truck ramps exist for the day they do. Know where they are on your route before you need them, and never rely on the brakes alone.
Where does the Colorado commercial chain law apply?
The State Patrol lists I-70 west of Morrison, Highway 9 between Frisco and Fairplay, US 50 west of Salida, US 160 west of Walsenburg, US 285 and all of US 550.
How many chains does a straight truck need in Colorado?
A straight truck with four drive tires needs chains on four tires, according to the State Patrol.
When is the Colorado commercial chain law in effect?
On the designated mountain highways it covers September 1 through May 31 for commercial vehicles over about 16,000 pounds, with chains required when conditions call for it.
How do I find out about Colorado chain requirements?
CDOT announces them through variable message signs, 511, cotrip.org and text alerts.
Does a Colorado CLP carry over if I add an endorsement?
No. CLP written test results are valid for only one CLP issuance. Adding a class or endorsement means retaking the knowledge tests and getting a new permit.
Can I transfer an out-of-state CDL to Colorado?
Yes, if it expired less than one year ago, with the written and skills tests waived. Out-of-state CLPs do not transfer.
Chain laws and CDL procedures change, so confirm current rules with the Colorado Division of Motor Vehicles, the Colorado State Patrol and CDOT before you travel or apply.