If you ski or board the Cottonwoods, your winter does not start when the lifts spin. It starts the first morning the Utah traction law light is flashing at the mouth of Big or Little Cottonwood Canyon and someone is deciding whether your tires make the cut.
Utah has tightened the rules for Big and Little Cottonwood Canyons, and enforcement is more real than it has ever been. Here is what Salt Lake City drivers need to know about the traction law this season, and how to get your car legitimately ready, from the team at Aposhian Garage in Millcreek, just down the road from both canyons.
What the Traction Law Covers
The Cottonwood Canyons traction law applies to SR-190 through Big Cottonwood Canyon and SR-210 through Little Cottonwood Canyon, the roads serving Brighton, Solitude, Snowbird, and Alta. When UDOT activates the traction law during winter conditions, every vehicle on those roads must meet minimum tire or traction device requirements.
The core requirements to remember:
- Two-wheel-drive vehicles need tires with the Three-Peak Mountain Snowflake (3PMSF) symbol on all four wheels, or chains on the drive wheels.
- All-wheel-drive and four-wheel-drive vehicles need at least M+S (mud and snow) rated tires on all four wheels. Chains or 3PMSF tires are still the better choice, but M+S is the legal minimum.
- Tread depth matters. Vehicles need at least 5/32 inch of tread when requirements are in effect. Worn out "winter" tires do not count.
Check your sidewalls before the season. The 3PMSF symbol is a mountain outline with a snowflake inside it. M+S appears as M+S, M/S, or M&S. If you are not sure what you have, we will look for you in thirty seconds when you drive by.
What Changed for This Winter
Recent updates made the law stricter and easier to enforce:
- Earlier activation. UDOT can now put traction requirements in place up to 24 hours before a storm arrives, instead of waiting for snow to start falling. Do not assume a dry road at 7 a.m. means the law is off.
- Real citations. Local police departments and the county sheriff's office can now issue tickets for traction law violations in the canyons. Compliance used to rely mostly on checkpoints and turnarounds. Now it can follow you home as a fine.
- A stricter storm designation. During major storms, a tighter set of requirements can apply, including the 5/32 inch tread minimum.
UDOT also runs a sticker program with free winter tire inspections at over 140 participating tire shops along the Wasatch Front through late February. The sticker tells canyon enforcement at a glance that your tires qualify, which can save you time on a powder morning.
The AWD Myth, One More Time
Every winter we hear it: "I have all-wheel drive, so I am fine." Along the Wasatch Front, that belief fills ditches every January.
All-wheel drive helps you accelerate on snow. It does almost nothing to help you stop or steer, because braking and cornering grip come entirely from your tires. A Subaru on worn all-season tires will out-accelerate a sedan on winter tires up a snowy grade, then need far more distance to stop at the bottom of it. This is exactly why the law still requires M+S or better tires on AWD vehicles: the drivetrain does not replace rubber.
If you make more than a handful of canyon trips a season, a dedicated set of 3PMSF winter tires is the single best safety upgrade you can buy. We wrote a full comparison of winter tires versus all-season tires for Salt Lake City's climate if you want to go deeper.
Your Ski Season Car Prep Checklist
Tires get you up the canyon, but they are only part of surviving a Utah winter of dawn patrols and stop-and-go canyon traffic. Before the first big storm, have these checked:
- Tires and tread depth. Confirm the rating (3PMSF or M+S), measure the tread, and check pressures. Cold weather drops tire pressure roughly one PSI for every 10 degrees.
- Battery. Cold starts are hard on batteries, and canyon parking lots at 15 degrees are where weak batteries go to die. A load test takes minutes.
- Cooling system and heater. Proper antifreeze protection keeps the engine safe, and your heater and defroster keep the windshield clear in traffic.
- Brakes. Long descents from Alta or Brighton demand healthy pads and rotors. If you feel vibration or hear squealing on downhill braking, fix it before the season.
- Wipers and washer fluid. Use winter-rated washer fluid, because summer fluid freezes on the glass exactly when visibility matters most.
- Emergency kit. Blanket, headlamp, snacks, water, a phone charger, and traction aids. Canyon closures and long interlodge waits happen every season.
A Local Note on Timing
Every year, the first traction law activation catches thousands of drivers with the wrong tires and every tire shop in the valley books out for two weeks. October is the sweet spot: inventory is available, appointments are easy, and you are legal before the first flakes fly.
Aposhian Garage is minutes from the mouths of both Cottonwood Canyons, and we have been getting Millcreek and Salt Lake City vehicles ready for ski season for decades. We will check your tires against the Cottonwood traction law in Utah, test your battery, and inspect your brakes in one visit. Schedule your ski season checkup today, and spend powder mornings in the lift line instead of the chain-up area.
Due for a ski season checkup? Aposhian Garage serves Millcreek and Salt Lake City drivers with thorough service for all makes and models. Call (801) 467-3344 or schedule your appointment.
Frequently Asked Questions
When the traction law is active on SR-210, two-wheel-drive vehicles need 3PMSF rated tires on all four wheels or chains on the drive wheels. AWD and 4WD vehicles need at least M+S rated tires on all four wheels. During major storms, a minimum tread depth of 5/32 inch applies.
No. AWD and 4WD vehicles must still have at least M+S rated tires on all four wheels when the law is active. AWD helps acceleration but does not improve braking or cornering on snow, which is why tire requirements still apply.
3PMSF stands for Three-Peak Mountain Snowflake, a symbol on the tire sidewall showing a mountain with a snowflake inside. It certifies the tire meets a severe snow service standard. It appears on dedicated winter tires and on some all-weather tires.
UDOT activates it when winter conditions warrant, and under the updated rules it can activate up to 24 hours before a storm arrives. Electronic signs and flashing lights at the canyon mouths indicate when it is active, and UDOT posts alerts online.
Yes. Under the updated rules, local police and the county sheriff's office can issue citations for traction law violations in the canyons, in addition to turning noncompliant vehicles around at checkpoints.
Yes. Utah has a waiver program for vehicles that fail emissions testing after the owner has spent a qualifying amount on emissions-related repairs. Your mechanic or the Utah DEQ can provide details on current waiver requirements and eligibility.
Written by the team at Aposhian Garage, providing auto maintenance and repair in Salt Lake City since 1928.
