Winter and Colorado’s Passenger Vehicle Traction Law

Fort Collins drivers know that a sunny fall afternoon can turn into a snowstorm by evening, especially in the mountains. For anyone heading west for skiing, hiking, or holiday travel, Colorado’s Passenger Vehicle Traction Law is something you cannot ignore. In this month’s blog post, we explain what the traction law requires, how to check whether your tires measure up, and why tread depth matters even if you never leave town.

When the Law Applies

The traction law is in effect on I-70 between Dotsero and Morrison every year from September 1 through May 31. The Colorado Department of Transportation can also implement it on other roads during winter storms. When it is active, drivers who are not properly equipped can be fined, and the fine is much higher if an under-equipped vehicle blocks a lane of traffic.

What the Law Requires

Every passenger vehicle needs tires with at least 3/16 of an inch of tread. Beyond that, requirements depend on your tires and how you drive. Tires marked M+S (mud and snow), tires with the mountain-snowflake symbol, or tires rated all-weather by the manufacturer generally qualify. Some vehicles, especially two-wheel drive models, may also need chains or an approved traction device. The rules have been updated in recent years, so check the current requirements on the CDOT website before a mountain trip.

How to Check Your Tread

Use a tire tread-depth gauge to check for at least 3/16 inch (6/32 inch) of tread. Measure several spots across the tread and around each tire, since tires can wear unevenly. The quarter test provides a quick wear check, but it cannot confirm that your tires meet Colorado’s minimum tread requirement.

Why Tread Matters Everywhere

Tread does more than keep you legal on I-70. Deep tread channels water, slush, and snow out from under the tire so the rubber can grip the road. Worn tires take longer to stop and are more likely to slide on an icy morning.

Other Things to Look For

• Uneven wear on one edge, which can point to an alignment problem
• Cracks or bulges in the sidewall
• Low pressure, which is common as temperatures drop
• Tires that are more than six years old, since rubber hardens with age and loses grip in the cold

A quick tire inspection now is far easier than finding out your tires fall short on a snowy mountain pass. If you want to have your tires inspected before the mountain roads turn icy, contact the service professionals at Campus Auto Repair to schedule your appointment.