Colorado Traction Laws for Denver and I-70 Drivers

Updated July 2026

Colorado’s traction law requires qualifying tires, chains, or an approved traction device when the rule applies. Beginning August 12, 2026, qualifying tires must have at least 3/16 inch of tread. They must also carry a mountain-snowflake, M&S, M+S, or M/S mark, or an all-weather rating from the manufacturer. The new law removes four-wheel drive and all-wheel drive as separate ways to comply. Drivetrain alone is not enough.

The rule applies from September 1 through May 31 on I-70 between Morrison and Dotsero. The Colorado Department of Transportation can also activate restrictions on other state highways during snow or ice.

Drivers leaving Denver for Floyd Hill, the Eisenhower-Johnson Memorial Tunnels, Vail Pass, or other mountain destinations should check their tires and equipment before the trip. If a winter crash has already happened, Strong Law’s Denver car accident lawyers can review how the road conditions, vehicle equipment, and each driver’s actions may affect the claim.

Important 2026 change: Until August 11, 2026, CDOT’s current guidance still treats a compliant AWD or 4WD vehicle as one option and chains or an approved device as the other. HB26-1237 takes effect August 12. It removes the separate AWD and 4WD references. The 2026–27 rule focuses on qualifying tires and tread, or chains and approved devices.

What does Colorado’s traction law require for the 2026–27 winter?

Starting August 12, 2026, a passenger vehicle can comply with an active Traction Law in either of these ways:

1. Use qualifying tires with at least 3/16 inch of tread. The tires must show a mountain-snowflake, M&S, M+S, or M/S symbol, or be rated all-weather by the manufacturer.
2. Carry and use tire chains or a CDOT-approved alternative traction device when required.

The signed 2026 act removes the law’s separate references to AWD and 4WD. Those systems may help a vehicle move, but they do not replace good tread or winter-rated tires. They also do not replace chains during an active Passenger Vehicle Chain Law.

Quick Colorado traction-law compliance table

This is a legal minimum, not a promise that a vehicle is safe for every storm. Tire condition, speed, visibility, and driver choices still matter.

Where and when does Colorado’s traction law apply?

The I-70 rule applies from September 1 through May 31 between milepost 259 near Morrison and milepost 133 at Dotsero. It covers the major mountain corridor west of Denver.

CDOT may also activate the Traction Law or Chain Law on any state highway. Drivers are notified through signs, COtrip, and official alerts. A restriction can change during a trip.

Before leaving Denver:

• Check COtrip for active restrictions, closures, cameras, and travel alerts.
• Confirm that every tire has the required tread and sidewall mark.
• Make sure chains, cables, or tire socks fit the vehicle.
• Learn how to install the device before the trip.
• Do not enter a closed highway or continue past an active restriction without the required equipment.

What changes on August 12, 2026?

Colorado enacted HB26-1237 in May 2026, and its traction-law change takes effect August 12. The 2025–26 rule treated AWD and 4WD vehicles with qualifying tires as a specific option. Many 2WD vehicles had to carry chains or an approved device on the I-70 corridor.

For 2026–27, a 2WD, AWD, or 4WD vehicle can meet the Traction Law with the required tire marks and tread. During a Passenger Vehicle Chain Law, every passenger vehicle must use chains or an approved device.

Older pages may still show the 2025 rule, so check CDOT’s current guidance and COtrip before a trip.

Which tires qualify under Colorado’s traction law?

A tire must have at least 3/16 inch of tread and meet one of the manufacturer-rating requirements in the law. Look on the tire sidewall for:

• The three-peak mountain-snowflake symbol
• M&S
• M+S
• M/S
• An all-weather rating from the manufacturer

The words “all-season” do not settle the question. Many all-season tires carry an M+S mark, but check the actual sidewall. A mountain-snowflake tire meets a stronger snow test than a tire marked only M+S. Either mark can satisfy the law when the tread is deep enough.

Studded tires are not a separate compliance method. A driver must still confirm the tread and rating or carry an approved device. The legal minimum also does not promise good grip in every mix of snow, ice, and slush.

How do you measure the 3/16-inch tread requirement?

Three-sixteenths of an inch equals 6/32 inch. The simplest accurate method is an inexpensive tire-tread gauge.

1. Park on a flat surface and set the parking brake.
2. Place the gauge in a main tread groove.
3. Check several places around each tire.
4. Record the lowest reading, not the average.
5. Check all four tires, including the rear tires on an AWD or 4WD vehicle.

A penny test checks for about 2/32 inch, far below Colorado’s 6/32-inch minimum. It cannot prove compliance. If a reading is close to 6/32, have the tires checked. Uneven wear can leave one part of a tire below the minimum.

Are AWD or 4WD vehicles automatically compliant?

No. Beginning August 12, 2026, AWD and 4WD are not separate compliance options in the law. The tires must meet the marking and tread rules, or the vehicle must have chains or an approved alternative device.

AWD and 4WD can send power to more wheels, but they do not create grip on worn tires. A vehicle can still slide while braking, turning, or going downhill. During a Passenger Vehicle Chain Law, AWD and 4WD vehicles must use chains or an approved device.

When can drivers use chains, cables, or tire socks?

Chains are one way to comply when tires do not meet the Traction Law. They become mandatory, along with approved alternatives, when CDOT activates the Passenger Vehicle Chain Law.

Colorado allows approved alternative traction devices, but approval is product-specific. CDOT lists certain cable chains and tire socks, including listed AutoSock and ISSE models. Check the approved product list. A generic “snow sock” may not qualify.

The device must fit the tire and vehicle. Some cars have little wheel-well space or limits on standard chains. Follow the owner’s manual and practice installation before the trip.

What is the difference between the Traction Law and Chain Law?

Colorado uses two passenger-vehicle restrictions:

Passenger Vehicle Traction Law

Beginning August 12, qualifying tires with at least 3/16-inch tread can satisfy the rule. Chains or approved devices are another option. The I-70 rule runs from September 1 through May 31. CDOT may activate it on other state highways.

Passenger Vehicle Chain Law

This is the final major step before a highway closes. Every passenger vehicle must use chains or an approved device. Winter tires, AWD, and 4WD are not enough by themselves.

Restrictions can change quickly. A driver who entered the corridor while the Traction Law was active may need to install chains or an approved device if CDOT raises the restriction.

What are the fines for violating Colorado’s traction law?

Current CDOT guidance lists these passenger-vehicle penalties:

• $100 fine plus a $33 surcharge for noncompliance
• $500 fine plus a $157 surcharge when the noncompliance results in the closure of a travel lane in one or both directions

Older articles may still cite $50 and $17. Commercial penalties are also different. Check CDOT’s guidance for current passenger rules.

A spinout can also lead to towing, storage fees, vehicle damage, and an injury claim. The tires, equipment, and driver’s choices may become part of the investigation.

Do rental cars and out-of-state vehicles have to comply?

Yes. Colorado’s traction and chain restrictions apply to vehicles using the covered highway, not only to Colorado residents.

Under SB25-069, rental companies must tell customers from September 1 through May 31 about the rule and whether the vehicle complies. Renters should still check the tires, tread, and included equipment.

If the rental lacks qualifying tires, ask for a compliant vehicle or an approved device. Do not assume an SUV complies because it has AWD. The same rule applies to visitors in their own cars.

Do commercial trucks follow the same rules?

No. Commercial vehicles have separate routes, chain rules, and fines. Colorado’s Must Carry Law covers more roads than the passenger I-70 corridor. It applies to covered commercial vehicles on marked routes from September 1 through May 31.

Drivers and carriers should use CDOT’s commercial guidance for current routes and equipment rules. After a truck crash, chain records, tire condition, dispatch choices, inspections, and weather planning may matter. Strong Law’s Denver truck accident lawyers can investigate those issues.

Can a traction-law violation affect fault after a winter crash?

It can, but a violation does not automatically decide every claim. The evidence still must show what caused the crash.

Worn or unmarked tires may show that a driver failed to follow the law or prepare for the road. That fact matters more if the vehicle lost grip and hit another car. It matters less if an unrelated event caused the crash.

Insurers may also review speed, following distance, braking, visibility, lane changes, and warnings. Snow and ice do not erase a driver’s duty to use care. Proof of legal tires also does not prove safe driving.

Colorado can reduce compensation when more than one person shares fault. The investigation must separate legal compliance from what caused the crash.

What evidence should you preserve after a Denver or I-70 winter crash?

Winter conditions change fast. Plows may clear the road, traffic can move debris, and video may be erased. If it is safe, preserve:

• Wide and close photos of snow, ice, slush, lane marks, grades, curves, and visibility
• Vehicle positions, impact points, tire tracks, debris, and guardrail damage
• Tire sidewall markings and tread-gauge readings for the vehicles involved
• Chains, cables, tire socks, packaging, receipts, and the device model
• Traction-law and chain-law signs
• COtrip screenshots showing restrictions, closures, cameras, weather, and time
• Dashcam video and photographs of nearby cameras
• Witness names and contact information
• The crash report, towing documents, repair records, and insurance messages

Do not stand in a lane or near moving traffic to take photos. I-70 crashes can cause another collision, especially near curves, tunnels, grades, and poor visibility.

Strong Law’s guide to what to do after a Denver car accident explains reporting, medical, insurance, and record steps. If video may exist, request and preserve Denver traffic-camera footage before it is erased.

Frequently asked questions about Colorado traction laws

Is Colorado’s traction law always active on I-70?

The I-70 rule applies from September 1 through May 31 between Morrison and Dotsero. CDOT can activate restrictions on other state highways. Check signs and COtrip during your trip.

Are winter tires required in Colorado?

Winter tires are not required on every road at all times. When the Traction Law applies, qualifying tires are one option. Starting August 12, they need 3/16-inch tread and the required mark or all-weather rating. Chains or an approved device are another option.

Is AWD or 4WD enough under Colorado’s 2026 traction law?

No. Starting August 12, drivetrain alone is not enough. An AWD or 4WD vehicle needs qualifying tires with 3/16-inch tread, or chains or an approved device.

What does the 3/16-inch tread requirement mean?

It means each tire needs at least 6/32 inch of tread. Use a tread-depth gauge and check several places on every tire. A penny test is not enough because it measures a much lower depth.

Are tire socks legal in Colorado?

Some tire socks are approved. Approval depends on the product and model. Check CDOT’s list before relying on one.

When does every passenger vehicle need chains?

Every passenger vehicle must use chains or a CDOT-approved alternative device when the Passenger Vehicle Chain Law is active. This includes AWD and 4WD vehicles with winter-rated tires.

What are the fines for violating Colorado’s traction law?

CDOT currently lists a $100 fine plus a $33 surcharge for noncompliance. If the violation causes a travel-lane closure, the amount can increase to a $500 fine plus a $157 surcharge.

Can a traction-law violation affect fault after a crash?

Yes. Bad tires or missing equipment may show that a driver failed to prepare. They do not prove full fault by themselves. The violation must have caused or added to the crash.

Talk with a Denver winter-crash lawyer

Winter-crash claims may depend on facts that disappear fast, including tire condition, active restrictions, video, road treatment, and alerts. Strong Law Accident & Injury Attorneys can investigate those facts and explain the law.

If you were injured in Denver or on the I-70 corridor, call 720-743-5046 for a free consultation. There is no fee unless we win your case. You can also learn more about the firm’s broader work on the Denver personal injury lawyer page.

This article gives general information, not legal advice. Restrictions, approved products, and road conditions can change. Check CDOT and COtrip before driving.