Colorado's Traction Law & Chain Law Explained

Q: What does Colorado's Traction Law require?

When the Colorado Department of Transportation activates the Traction Law (often called Code 15), every vehicle on the affected stretch of road must meet one of a few requirements to be legal. You need either four-wheel or all-wheel drive with adequate tires, or tires with a mud-and-snow (M+S) or a mountain-snowflake (3PMSF) rating, or an all-weather tire, and in all cases your tires must have at least one-eighth of an inch of tread depth. Alternatively, you can run tire chains or an approved traction device. The Traction Law is the more common, less severe of Colorado's two winter driving codes, and it is frequently in effect on I-70 in the mountain corridor during and after storms. Adequate tread and a proper winter or all-weather tire are the simplest way for most Denver drivers to comply. Denver CO Tire Shop can check whether your tires qualify — call (720) 571-1736.

Q: What is the difference between the Traction Law and the Passenger Vehicle Chain Law?

They are two escalating levels of the same winter driving system. The Traction Law (Code 15) is the lower level and only requires appropriate tires with sufficient tread, or chains if your tires do not qualify. The Passenger Vehicle Chain Law (Code 16) is the highest level, activated in severe conditions, and at that point every vehicle, including four-wheel and all-wheel drives, must have chains or an approved alternative traction device such as an AutoSock or textile traction device actually installed on the tires. In other words, under the Traction Law good winter tires are usually enough, but under the Chain Law nearly everyone must chain up regardless of drivetrain. Colorado activates these codes based on conditions, most often on I-70 west of Denver, and violating them carries fines that increase significantly if your vehicle blocks the roadway. Denver CO Tire Shop can help you get winter-ready — call (720) 571-1736.

Q: How much is the fine for violating Colorado's traction or chain law?

The fines are significant and are designed to discourage unprepared drivers from getting stuck and blocking mountain highways. Being on the road without the required equipment when a code is in effect carries a fine of over one hundred dollars with surcharges, and if your vehicle blocks the roadway because you were not properly equipped, the penalty rises to more than six hundred and fifty dollars with surcharges. Beyond the fine, a stuck vehicle on I-70 can close a lane for hours and put you and others at risk, so the practical cost of being unprepared is much higher than the ticket alone. Because the codes can be activated with little warning when a storm moves in, the safest approach is to be equipped before you head into the high country rather than gambling on the conditions. Denver CO Tire Shop can make sure you are ready — call (720) 571-1736.

Every Colorado winter, the same scene plays out on I-70: a storm moves in, CDOT activates a traction code, and drivers who assumed they'd be fine end up ticketed, stuck, or both — sometimes shutting down the corridor for everyone behind them. The rules aren't complicated once you understand them, and getting your tires sorted before ski season is far cheaper than a fine or a tow off the shoulder near Georgetown. Let's break it down.

Two Laws, Two Levels

Colorado uses an escalating system. Think of it as two rungs on the same ladder — the state activates whichever level matches the conditions, most often on I-70 west of Denver but potentially on any affected highway.

Level 1: The Traction Law (Code 15)

This is the more common, lower-severity code. When it's active, your vehicle must meet one of these to be legal:

4WD or AWD with adequate tires (and at least 1/8" tread), or
Tires rated M+S (mud and snow), or
Tires with the 3PMSF (three-peak mountain snowflake) rating, or
An all-weather tire, or
Chains or an approved traction device if your tires don't otherwise qualify.

The universal requirement underneath all of those: at least 1/8" of tread depth — that's 4/32", notably deeper than the 2/32" legal minimum for tires generally. Bald all-seasons won't cut it even if they're technically "M+S" stamped.

The tread catch: Colorado's Traction Law requires 1/8" (4/32") of tread — double the normal 2/32" legal minimum. A tire can be street-legal and still fail the Traction Law. Check yours before you head up. Our guide on when to replace your tires covers how to measure.

Level 2: The Passenger Vehicle Chain Law (Code 16)

This is the highest level, activated in severe conditions. When Code 16 is in effect, every vehicle — including 4WD and AWD — must have chains or an approved alternative traction device (like an AutoSock / textile traction device) actually installed on the tires. Good winter tires alone are no longer enough at this level; nearly everyone has to chain up regardless of drivetrain.

So the simple mental model: under the Traction Law, proper winter or all-weather tires usually keep you legal. Under the Chain Law, you're putting chains on no matter what you drive.

What It Costs to Ignore Them

The fines are deliberately steep because an unprepared stuck vehicle can close a mountain highway for hours:

On the road without required equipment: a fine of over $100 with surcharges.
Blocking the roadway because you weren't equipped: more than $650 with surcharges.

And that's just the ticket — a vehicle stuck on I-70 in a storm is a genuine safety hazard to you and everyone else on the road. The real cost of being unprepared is almost always higher than the fine.

Get Traction-Law Ready in Denver

Not sure if your tires qualify for the Traction Law? Denver CO Tire Shop will check your tread and ratings and tell you straight whether you're legal for I-70 — before the next storm.

📞 Call (720) 571-1736 Tire Sales

Decoding the Tire Ratings

The sidewall stamps that matter for these laws:

M+S (Mud + Snow): a basic designation found on most all-season tires. It satisfies the Traction Law's tire requirement if you also meet the 1/8" tread rule — but M+S tires are tested far less rigorously than 3PMSF tires for actual snow performance.
3PMSF (Three-Peak Mountain Snowflake): the little mountain-and-snowflake symbol. This tire has passed real snow-traction testing and is what you actually want for serious mountain driving. Both dedicated winter tires and many all-weather tires carry it.

If you're weighing which type to run, our breakdown of winter vs. all-season vs. all-weather tires explains the trade-offs for Colorado driving, and choosing tires for Colorado weather helps you match tires to how and where you drive.

How to Know When a Code Is Active

CDOT activates and lifts these codes based on real-time conditions, sometimes with little warning as a storm rolls in. Before heading into the high country, check COtrip.org or the CDOT app for active codes on your route, watch for the overhead message boards on I-70, and when in doubt, assume mountain travel in winter means you should already be equipped. The codes come on fast; your tires can't.

One More Thing for AWD Drivers

Colorado is AWD country, and AWD helps you comply with the Traction Law — but remember it doesn't exempt you from the Chain Law, and it only helps if your tires are matched and have real tread. A worn or mismatched set undercuts the very traction you're counting on. We covered why in why all four AWD tires must match.

The Bottom Line for Denver Drivers

The Traction Law and Chain Law aren't there to trip you up — they exist because unprepared vehicles cause the pileups and closures that make I-70 miserable every winter. Run a 3PMSF-rated winter or all-weather tire, keep at least 1/8" of tread, carry chains for Code 16 days, and check COtrip before you drive up. Do that and these laws become a non-issue — you're just the driver who's already ready when the snow starts.

Frequently Asked Questions

What does Colorado's Traction Law require?

When CDOT activates the Traction Law (Code 15), your vehicle must meet one of these: 4WD/AWD with adequate tires, or tires rated M+S or 3PMSF, or an all-weather tire — and in every case at least 1/8" (4/32") of tread. Otherwise you need chains or an approved traction device. It's the more common, lower-severity code and is frequently active on I-70 in the mountains during and after storms. A proper winter or all-weather tire with real tread is the simplest way to comply. We can check if your tires qualify — call (720) 571-1736.

What's the difference between the Traction Law and the Passenger Vehicle Chain Law?

They're two levels of the same system. The Traction Law (Code 15) is lower and only requires appropriate tires with enough tread, or chains if your tires don't qualify. The Chain Law (Code 16) is the highest level, activated in severe conditions, and requires every vehicle — including 4WD and AWD — to have chains or an approved traction device actually installed. So under the Traction Law good winter tires usually suffice; under the Chain Law nearly everyone must chain up regardless of drivetrain. Get winter-ready — call (720) 571-1736.

How much is the fine for violating Colorado's traction or chain law?

Being on the road without required equipment when a code is active carries a fine of over $100 with surcharges. If your unequipped vehicle blocks the roadway, it rises to more than $650 with surcharges. Beyond the fine, a stuck vehicle can close an I-70 lane for hours and endanger everyone, so the real cost of being unprepared is much higher than the ticket. Because codes activate with little warning, it's safest to be equipped before you head up. We'll make sure you're ready — call (720) 571-1736.