Utah's Traction Law in the Cottonwood Canyons: What You Actually Need on Your Car

Quick answer: When UDOT activates the traction law in Big or Little Cottonwood Canyon, every vehicle needs at least 5/32 inch of tread depth. AWD and 4WD vehicles need M+S or 3PMSF tires on all four wheels. Two-wheel-drive vehicles need 3PMSF (three-peak mountain snowflake) tires on all four wheels - M+S alone does not qualify - or chains on at least two drive wheels. Violating it is an infraction carrying a fine of up to $750.

Updated September 2026 for the 2026–27 ski season.

The Reality Check for Cottonwood Canyon Drivers

Big and Little Cottonwood aren't ordinary mountain roads. They're narrow, steep, avalanche-prone corridors that dump thousands of skiers onto two lanes of pavement every storm morning - and when one unprepared sedan loses traction on a switchback, the whole line stops behind it. That's the "red snake" everyone complains about on powder days, and the snow itself rarely causes it. Vehicles that shouldn't be on the road cause it.

SR-210 - Little Cottonwood Canyon - has the highest highway avalanche hazard index of any major road in the United States and crosses 64 avalanche paths, according to Alta Ski Area. That's the context for everything that follows.

Enforcement has tightened accordingly. Under changes UDOT announced in November 2025, officers from Cottonwood Heights PD, Sandy PD, and the Salt Lake County Sheriff's Office can now write traction-law citations alongside the Utah Highway Patrol. During restricted periods, officers at the canyon mouths check vehicles before letting them up, and there's no negotiating your way past a tread-depth measurement. Get turned around, and you've lost your ski day. Get through unprepared and slide off, and you've blocked a road that emergency crews need.

The thesis is simple, and it runs against what most drivers assume: your drivetrain badge doesn't determine whether you're legal in these canyons. Your tires do - and for two-wheel-drive vehicles, the tires have to meet a higher standard than they do on an AWD car.

What Is the Utah Traction Law?

The traction law is Utah administrative rule R920-6, which lets UDOT and law enforcement impose winter equipment requirements on specific highway segments during severe conditions. It isn't in effect all winter - it switches on when the beacons at the canyon mouths start flashing.

The rule is written in three classes, and knowing which one you're under matters:

• Class 1 applies only to vehicles over 12,000 lbs GVW - buses, semis, some RVs. Most drivers never encounter it.
• Class 2 applies to all vehicles and is the standard restriction on routes like I-80 through Parleys Canyon.
• Class 3 is the newest and strictest tier, created in 2025, and it exists specifically for Big and Little Cottonwood. It includes the 5/32-inch tread mandate.

The Requirements, by Drivetrain

When the traction law is active in the Cottonwoods, this is the table that decides whether you go up:

Your vehicle	Minimum legal setup	Tread depth
AWD / 4WD	M+S (or M/S) tires on all four wheels. 3PMSF tires or chains/snow socks also qualify and perform better.	5/32"
2WD (front or rear)	3PMSF tires on all four wheels. M+S is not sufficient. Chains or snow socks on at least two drive wheels are the alternative.	5/32"
Over 12,000 lbs GVW	Chains on drive tires, or AWD/4WD with M+S or 3PMSF	5/32"

That 2WD line is where most people get it wrong. The old mental model - "any snow-ish tire plus chains in the trunk" - is not the current rule. If you drive a front-wheel-drive Civic or Corolla up Big Cottonwood on a storm day, you need the three-peak snowflake symbol on all four sidewalls, or chains.

M+S vs. 3PMSF: Not the Same Thing

M+S (Mud and Snow) is a tread-pattern designation - essentially the manufacturer's word that the tire has open grooves and meets Rubber Manufacturers Association geometry guidelines. No performance test is involved.

3PMSF (Three-Peak Mountain Snowflake) means the tire passed an actual snow-traction test and is rated for severe snow service. The rubber compound stays pliable in the cold instead of turning into a hockey puck.

Both are accepted for AWD and 4WD. Only 3PMSF is accepted for 2WD. And regardless of what's legal, the three-peak snowflake is what actually stops you.

How to Check 5/32" - and Why the Coin Tricks Don't Work Here

The coin tests everybody quotes measure the wrong depths. A penny (Lincoln's head) checks the 2/32" legal-minimum-for-anything threshold. A quarter (Washington's head) checks 4/32". Neither one measures 5/32, and 4/32" of tread will get you turned around at the canyon mouth even though it passes the quarter test.

Buy a tread depth gauge - they run about $5 at any parts store - and check three spots per tire: inside edge, center, outside edge. Uneven readings mean an alignment or inflation problem, which matters regardless of where you're driving. Or get a free inspection (more on that below) and let someone else do the measuring.

Does AWD Satisfy the Traction Law?

Only if the tires do. All-wheel drive is an acceleration technology - it splits torque so you don't spin a wheel pulling away from a stop sign. It does little for braking distance and nothing for lateral grip in a corner. Those jobs belong entirely to the rubber.

The test data is blunt about this. In Consumer Reports ice-braking tests, an all-wheel-drive RAV4 needed 57 feet to stop from 12 mph on all-season tires and 33.7 feet on winter tires - the same vehicle, the same driver, roughly 40% less distance, entirely from the tires. Broader testing from the Tire and Rubber Association of Canada puts winter-tire braking distances up to 30% shorter than all-seasons.

That's the gap most drivers never close. All-season compounds stiffen as temperatures drop toward freezing, and a stiff tire can't conform to the micro-texture of packed snow. It's the single most common reason a capable-looking SUV ends up sideways on the S-curves below Snowbird. A Subaru on worn all-seasons and a Camry on worn all-seasons stop in roughly the same unhappy distance on canyon ice.

What Does It Cost If You Ignore It?

A traction law violation is an infraction punishable by a fine of up to $750. That's the ceiling, not a guarantee, but it's a real number, and it's the cheap outcome.

The expensive outcome is sliding off and blocking the road. A stuck vehicle in a two-lane canyon during a storm means tow bills, hundreds of drivers stopped behind you, and - if the closure interferes with avalanche control - a significantly worse afternoon than a citation. Set against winter tires, the math isn't close.

Where and When the Law Applies

The Class 3 restriction applies to SR-210 (Little Cottonwood, serving Snowbird and Alta) and SR-190 (Big Cottonwood, serving Solitude and Brighton). Enforcement is concentrated at or near the canyon mouths, where officers check vehicles before they commit to the climb.

The timing catches people off guard. Thanks to HB 196, passed in the 2025 legislative session, UDOT can now activate the restriction up to 24 hours before a forecast storm arrives. You can leave a dry driveway in Sandy at 6 a.m. and hit an active restriction at the Wasatch Boulevard turnoff. Plan for the forecast, not the weather outside your window.

Separately, Alta notes that state law expects snow tires or chains on the canyon road between November 1 and May 1 - so the window is longer than most people assume, even on days the beacons are dark.

Heading to the Wasatch Back instead? I-80 through Parleys, US-40 in Summit and Wasatch counties, and Marsac Avenue in Park City carry their own Class 1 and Class 2 restrictions during major storms. The requirements are a notch below Class 3, but the same tire standards still apply regardless of which side you ski.

How to Check Status Before You Leave

• @UDOTcottonwoods on X - real-time restriction levels and traction device status
• UDOT Traffic app (udottraffic.utah.gov) - road conditions, closures, canyon cameras
• Resort websites - Alta, Snowbird, Brighton and Solitude all post canyon status on storm mornings

One detail worth knowing: UDOT posts a traction device status alongside the restriction. "In or on vehicle" means chains can ride in the cargo area. A chains-on status means installed before you climb - and a canyon shoulder in a storm is a miserable place to learn how your chains work. Practice once in the driveway.

The UDOT Sticker Program - What It Does and Doesn't Do

UDOT runs a free, voluntary Cottonwood Canyons Sticker Program: take your vehicle to a participating tire shop, get the tires inspected at no charge, and if you pass, you get a windshield sticker showing your vehicle met the standard. Last season the program ran November 13 through February 28 across more than 140 shops along the Wasatch Front - Discount Tire, Big O, Les Schwab, Burt Brothers and others. UDOT announces each season's dates and shop list in the fall.

Be clear on what the sticker is, though, because this gets oversold. UDOT states plainly that stickers are not required to drive the canyons, don't guarantee access, and don't exempt you from inspection - "vehicles may still be subject to inspection at the discretion of law enforcement." It confirms, in advance and for free, that you meet the standard, so you're not finding out at the canyon mouth on a powder morning.

It appears to be moving the needle. In UDOT's participant survey, 86% said they'd noticed more properly equipped vehicles in the canyons, and 71% said enforcement is improving overall travel.

Best Used Vehicles for the Canyons on a Budget

The used vehicles that handle Utah snow best aren't exotic. Subaru's symmetrical all-wheel drive - Outback, Forester, Crosstrek - has earned its Wasatch Front reputation honestly, and used examples come through our lot regularly. Toyota's RAV4 and Highlander systems are less aggressive but paired with drivetrains that shrug off 150,000 miles. Honda's CR-V AWD is the quiet, cheap-to-own option. If you need utility along with canyon access, a used truck with a real transfer case and low range gives you options a crossover doesn't, and our SUV inventory rotates constantly through ski season. Selection changes week to week - we'll tell you what's mounted on a vehicle before you take it home.

One rule matters more than any badge: a ten-year-old AWD wagon on fresh 3PMSF tires will out-drive a two-year-old SUV on worn all-seasons, in every storm. Drivetrain is a convenience. Tread is the whole game. (Worth knowing the middle ground, too - all-weather tires carry the 3PMSF rating and are a reasonable year-round compromise if you don't want to swap sets twice a year, though a dedicated winter tire still wins on ice.)

So build tires into your budget, not after it. When you're negotiating a used vehicle, ask what's on it and what the tread measures. Tires are a legitimate part of the conversation - factor a set into the deal, or plan to buy them in your first month of ownership.

Your Canyon Readiness Checklist

Five things to confirm before you point the car uphill:

• Tires - 3PMSF on all four if you're 2WD; M+S or better if you're AWD/4WD. At least 5/32" of tread everywhere, measured with a gauge, not a coin.
• Drivetrain - AWD or 4WD actively engaged, not sitting in 2WD. If you're 2WD without 3PMSF tires, chains on at least two drive wheels, in a size that fits, that you've installed once before in daylight.
• Verification - get the free UDOT inspection sticker early in the season, before the first big storm. It won't exempt you from a check, but it means you already know the answer.
• Timing - check the restriction level before leaving home. Restrictions can go active up to 24 hours ahead of the snow.
• Visibility - clear snow off the roof, hood, lights and license plate. A slab of roof snow sliding onto your windshield at a switchback is its own kind of emergency, and it's how you blind the driver behind you.

Frequently Asked Questions

Does AWD mean I can skip snow tires in the Cottonwood Canyons?

No. AWD and 4WD vehicles still need M+S or 3PMSF tires on all four wheels with 5/32" of tread when the traction law is active. AWD helps you accelerate; it does essentially nothing for stopping or cornering on ice.

What's the fine for violating Utah's traction law?

It's an infraction carrying a fine of up to $750. If your non-compliant vehicle blocks the canyon, you can also be on the hook for towing and closure costs.

Do I need the UDOT sticker to drive up the canyon?

No. The sticker program is free and voluntary, and UDOT makes it clear that a sticker doesn't guarantee canyon access or exempt you from a roadside inspection. It confirms in advance that you meet the standard.

Are all-weather tires good enough, or do I need dedicated snow tires?

All-weather tires carry the 3PMSF rating, so they satisfy the traction law for any drivetrain - including 2WD. A dedicated winter tire still stops shorter on ice. If you make the canyon drive a handful of times a season, all-weathers are a fair compromise; if you're up there every weekend, buy winters.

Can I check 5/32" with a quarter?

Not reliably. A quarter measures 4/32" and a penny measures 2/32" - both are below the canyon requirement. Use a $5 tread depth gauge, or get a free inspection at a participating shop.

What used vehicles handle the Cottonwood Canyons best on a budget?

Subaru Outback, Forester and Crosstrek, Toyota RAV4 and 4Runner, Honda CR-V AWD, and Jeep Grand Cherokee all come through regularly in the $10,000–$25,000 range. What's on the tires matters more than which badge you pick. Call (801) 561-2727 and we'll tell you what's on the lot this week.

Finding a Winter-Ready Vehicle at Peterson Auto Sales

If you're not sure whether your current tires clear 5/32", stop by the lot at 8498 South State Street in Midvale and someone will measure them with you - no appointment, no obligation, no sales pitch attached. Knowing where you stand before the first November storm is worth the ten minutes.

If the answer is that you need a different vehicle, our AWD and 4WD inventory rotates constantly - Subarus, RAV4s, 4Runners, Grand Cherokees - and the price on the window is the price you pay. Flat $289 doc fee, free CARFAX up front, no junk add-ons bolted on at the desk, and a full tank of gas with every car we sell. Our salespeople aren't paid on commission, so nobody is quietly calculating what to push you toward. Trade-ins are welcome with a free same-day appraisal, and you don't have to buy from us to sell us yours.

Worried your credit history rules you out of a safe winter car? It usually doesn't. Peterson works with more than 40 lenders, including subprime specialists and a First-Time Buyer program built for people with thin files.

Family-owned in Midvale since 1965 and two-time Utah Quality Dealer of the Year (1989 and 2023). We're open Monday through Friday 9am–6pm and Saturday 9am–5pm. Take your time, ask hard questions, and get in touch or call (801) 561-2727 when you're ready.

Traction law requirements are set by UDOT and can change. Confirm current requirements at cottonwoodcanyons.udot.utah.gov before you drive.