Are Mud Tires Legal in Winter? What Traction and Chain Laws Accept

Answers · Winter

Yes, you can drive on mud tires in winter. Whether they count when a traction or chain law is switched on depends on the state, the sidewall marking, how much tread is left and whether the truck is four-wheel drive. Here is what five western states’ own transportation departments say, read on 8 October 2026.

• 5 states checked
• 4 accept M+S on 4WD/AWD
• 1 wants 3PMSF or chains
• By Cole Harlan · Last reviewed 8 October 2026

The short answerby Cole Harlan, who writes Mud Tires

From official sources

Are mud tires legal in winter, and do they meet chain laws?

Yes, they are legal. As of October 2026, an M+S-stamped mud tire satisfies the everyday traction rules in Colorado, California, Washington and Utah, mostly on 4WD or AWD and only above a minimum tread depth. Oregon is the exception: only tires with the three-peak mountain snowflake (or studs) count there, so carry chains.

None of that survives the top level of any state’s rules. When California posts R3, Colorado switches on its chain law or Washington signs “chains required on all vehicles”, four-wheel drive and mud tires stop counting and every vehicle needs chains or an approved traction device.

Rules change between winters, and signs on the road override any summary, including this one. Check the state’s own page before you go.

State by state: what counts when traction rules are on

What each state’s transportation department says, in its own terms. “M+S” covers the M/S, MS and “mud and snow” stampings. 3PMSF is the three-peak mountain snowflake symbol.

Read 8 October 2026 from each department’s own page (links under Sources). Colorado’s list is from its “Traction Law Updates – Fall 2025” notice.

Does an M+S stamp make a mud tire a snow tire?

In law, often yes. In performance, no. California defines a snow-tread tire as one with “a relatively deep and aggressive tread pattern”, and the M+S stamp is how you prove it at a checkpoint, which a mud-terrain passes easily. But M+S is awarded on tread geometry, not on a snow test. Only the three-peak mountain snowflake requires a measured result on packed snow, and almost no mud-terrain carries it. We cover the difference in are mud tires any good in snow?

That gap is exactly why Oregon and Utah treat the two markings differently: Oregon’s traction-tire definition names the mountain/snowflake emblem, and Utah accepts M+S only on four-wheel and all-wheel drive.

What about a two-wheel-drive truck on mud tires?

Of the five states, only Washington accepts a 2WD passenger vehicle on M+S traction tires when traction tires are required, and California accepts it only at the lowest level (R1), only under 6,000 lb gross weight and only with chains in the truck. Utah sets 3PMSF as the minimum for 2WD. Colorado’s current list pairs every tire option with AWD/4WD. Oregon does not count M+S as a traction tire at all. A 2WD truck on mud tires should plan on chains.

When do you need chains anyway?

• California R2: chains or traction devices on everything except 4WD/AWD with snow-tread tires on all four wheels. R3: every vehicle, no exceptions. The speed limit with chains on is 25 or 30 mph.
• Colorado Chain Law: every vehicle needs chains or an approved alternative traction device. CDOT lists a $100 fine plus a $33 surcharge for not complying, and $500 plus $157 if it leads to a lane closure.
• Washington “Chains Required”: all vehicles except 4WD/AWD (which must still carry them), $500 fine. “Chains Required On All Vehicles” includes 4WD/AWD. Studded tires do not meet chain requirements.
• Oregon conditional closures: ODOT can require chains on all vehicles, even four-wheel drive, and says traction tires are then not enough. Its own example is Interstate 5 over Siskiyou Pass.
• Towing or heavy trucks: California, Washington and Oregon all write separate, stricter rules for trailers and for vehicles over 10,000 lb GVW.

Before winter: a five-minute check

1. Read the sidewall. Look for M+S (or M/S, MS, “Mud and Snow”) and the mountain snowflake. Write down which you have.
2. Measure the tread with a depth gauge in the main grooves. Compare it with the state’s minimum: 6/32 in Colorado, 4/32 in Washington, 5/32 in Utah’s Cottonwood Canyons. Our when to replace mud tires guide explains wear bars.
3. Buy chains or an approved traction device that fit your actual tire size, before the first storm. Caltrans says to check your vehicle maker’s guidance on chain use.
4. Check the state’s live road-condition page (COtrip, Caltrans QuickMap, WSDOT, TripCheck, UDOT Traffic) before you leave. Utah says you may need to comply up to 24 hours before a storm.
5. If you live with real snow and ice, consider a dedicated winter set or a 3PMSF all-terrain. Our mud tires vs all-terrain page sets out the trade.

Related on Mud Tires

Are mud tires any good in snow? · When to replace mud tires · Mud tires vs all-terrain · All Mud Tires answers

Sources

• Colorado Department of Transportation, Passenger Vehicle Traction and Chain Laws (codot.gov)
• Caltrans, Chain Controls / Chain Installation (dot.ca.gov), citing California Vehicle Code §558 and §605
• Washington State Department of Transportation, Winter Driving Guide (PDF, wsdot.wa.gov), citing WAC 204-24-050
• Oregon Department of Transportation, Oregon Chain Law (tripcheck.com), citing OAR Chapter 734, Division 17
• Utah Department of Transportation, Snow Tire, Chain & Traction Device Requirements (udot.utah.gov), citing Utah Administrative Code R920-6

All five pages read 8 October 2026. This is a summary of official guidance, not legal advice; posted signs and officers at checkpoints have the final word.