What is the “Traction Law” and what are “Traction Devices”?

It is important to ensure that you have traction devices appropriate for winter driving conditions, snow-worthy tires or chains are not just for your safety, it is the rule of the road. Traction devices are required during severe winter weather conditions on roadways throughout Utah, including Big and Little Cottonwood Canyons.

AWD/4WD: M + S or M/S tires is the minimum requirement. Traction devices such as chains or 3 peak mountain snowflake (3PMSF) tires are also acceptable.

2WD: 3 peak mountain snow flake (3PMSF) tires (on all four tires) is the minimum requirement. Traction devices such as chains are also acceptable.


“Why haven’t you put in the traction law into effect yet?”

We appreciate the comments and inquiries you’ve sent our way about the #TractionLaw so we wanted to take some time to talk about it a little more and hopefully answer some questions for you.

Spoiler Alert: changes are in the works. Check the last slide for more information.

And for a refresher on #TractionDevices make sure to check the Traction Law story highlight or visit the website, link in bio.

Now swipe left!
What is the actual rule?
The current Utah Administrative rule (Rule R920-6. Traction Device/Tire Chain Requirements) states that the #TractionLaw goes into effect when road conditions warrant, a decision made by UPD or UDOT. Per Utah code, 2/32 is the minimum tire tread depth needed for all roadways.
You know it’s going to snow, why aren’t you requiring the devices in the morning before people go up?
It’s important to note that under the existing rule, requiring traction devices is based on current road conditions, not predicted conditions. When chains are installed and drive on dry roads, it can damage both the vehicles and the roadway. Having chains on when the roads are dry also makes it difficult for drivers to steer and travel at posted speed limits.
Why has it been taken in and out of effect throughout the day?
Restrictions are based on current road conditions. The #TractionLaw is put into effect as road conditions become difficult for motorists to navigate. Conditions can change by the hour in the mountains, and the #TractionLaw is not an uphill only rule. Drivers need to be prepared to go downhill during winter driving conditions, and prepared for changing conditions when they head uphill - even if it’s a bluebird day.
Why isn’t someone at the mouth every single time the #TractionLaw is in effect?
UDOT and UPD have to balance available resources and operational needs. Both agencies need to respond to in-canyon incidents and also have coverage areas beyond the canyons. UDOT and UPD reassess conditions and are actively assisting travelers throughout the day, regardless of conditions. Coordination is ongoing among these agencies to address staffing/resources to enable more frequent tire checks at the base.
So who is actually causing all these slide offs? I see an awful lot of 2WD vehicles with out of state plates heading up the canyons.
It’s true, plenty of out of state 2WD cars without traction devices make it up the canyons and slide off. However, many vehicles involved in slide offs or crashes are Utah residents who have met the criteria of the #TractionLaw and would have been allowed up. Poor tire tread for snow, driver difficulty in navigating winter conditions and speed also contribute to slide offs/cashes. It is critical that all travelers (even the locals) have confidence in their winter driving abilities. If you don’t, we recommend trying out the ski bus instead of white-knuckling it.
Snow tires are expensive, why should I buy some? What is the difference between those and M+S or M/S tires?
M+S and M/S tires are the same thing. Tire tread pattern is the only requirement for an M+S or M/S rating, while 3PMSF tires (snow tires) are required to meet performance standards on a snow-packed track that indicate improved traction and control in winter conditions. This is accomplished by a different rubber compound that provides more grip on snow and on cold pavement than an all-season tire.
So what good were the stickers you handed out at the beginning of the season?
The 5,000 stickers we gave out this year mean that there are at least 5,000 vehicles properly equipped for driving in the canyons when traction devices are required. Additionally, when #TractionLaw is being enforced, vehicles with stickers move through these checkpoints quickly and help the overall flow of traffic.
Is UDOT doing anything else to address these issues with the current #TractionLaw?
  • UDOT is working on adding a class 3 segment to the rule which would require traction devices to be in the vehicle (chains) or on (M+S / 3PMSF rated, snow tires) at all times. #SR210 and #SR190 would be included under the class 3 segment.
  • The #TractionLaw would be in effect from October 15 to March 31, regardless of conditions.
  • UDOT will observe if these changes make a difference in reducing slide offs/crashes as a result of unprepared vehicles to determine if the new rule should remain in place.
Get Involved with Changes to the Current #TractionLaw
These changes are currently being reviewed internally by UDOT. Next up? A two week public comment period. If you want your voice heard regarding these changes, make sure to submit a comment during this time! We will share an update when the public comment period dates are known and where you can go to submit a comment. We recommend sharing your ideas through this process, as commenting here or through DM does not count as a formal comment.


UDOT wants you and your family to stay safe on the roads this winter. By following these tips and advice, you’ll be ready for winter driving. And don’t forget: Ice and Snow, Take it Slow!

You can open the PDF below to find winter driving tips in four areas:

  • Be Prepared
  • Be Aware
  • Be Cautious
  • Staying Safe Around Snowplows


Winter weather driving is challenging, especially in the Cottonwood Canyons. If you are visiting from out-of-town and renting a vehicle, check with the rental company to verify that your vehicle is equipped with four-wheel drive (4WD) or all-wheel drive (AWD) and the correct tires by showing them this card: