Colorado's annual commercial vehicle chain law will take effect on September 1. This rule is important for truckers moving freight across the Rockies, especially when the snow starts to fly.

The basics: From September 1 through May 31, truckers driving vehicles over 16,000 pounds need to carry chains when running certain routes, like I-70 from Morrison to the Utah border and several other state and U.S. highways.

• This rule also covers buses, auto transporters, and even hot shot pickups pulling trailers that meet the weight rules.
• Failing to carry or use chains can mean big fines: $50+ if you don't have them, $500+ if you don't chain up when required, and over $1,000 if you wind up blocking the road due to not chaining.
• Some setups, like tandem axle combos or straight trucks, have specific chain or alternative traction device requirements. There's also an exception to protect truck hydraulics on auto transporters.

Enforcement: Colorado State Patrol regularly checks trucks for compliance during the season, and fines add up quick if you aren't ready.

For details: You can find the full list of routes and exact chain requirements for your rig, according to CDOT.