Semi Truck Tire Sizes
Winter and Seasonal Truck Tires
Seasonal tire requirements for commercial trucks vary by state, road condition, and route. A tire that meets standard highway requirements may not satisfy a chain law, traction law, or seasonal restriction in effect on certain roads.
This page provides background on tire markings and seasonal categories. Check the current rules for every state and jurisdiction in your operating area — requirements change and enforcement varies.
Key seasonal tire markings
| Marking | What it means | Standard |
|---|---|---|
| M+S | Mud and Snow — tire meets minimum ASTM void ratio and tread requirements for mud and snow traction | ASTM F1805; widely available, broad category |
| 3PMSF | Three-Peak Mountain Snowflake — tire passed a severe-snow traction test exceeding M+S requirements | North American Tire Testing standard; more rigorous than M+S |
| All-season | Marketing term, not a regulated standard; most all-season truck tires also carry M+S | Not a defined legal category for compliance purposes |
| Winter / Snow | Designed specifically for cold-weather performance; may carry 3PMSF symbol | Verify specific markings for the applicable rule |
Chain laws and traction laws
Many western and mountain states operate chain laws and traction laws that specify minimum tire requirements for commercial vehicles operating during certain weather or road conditions. Requirements commonly specify: M+S-rated tires with minimum tread depth, or chains. Some jurisdictions distinguish between requiring M+S only, requiring 3PMSF, or requiring chains regardless of tire type. Enforcement and penalty vary by state.
States with active seasonal requirements (examples)
States with significant seasonal commercial vehicle tire or chain requirements include California, Colorado, Nevada, Oregon, Washington, Idaho, Wyoming, Montana, and others. This list is not exhaustive and requirements change seasonally and by road corridor. Always check current state DOT rules for each state in your route, and check the current season's requirements — these are not static year-round rules.
Tread depth for winter conditions
Federal minimums (4/32 inch steer, 2/32 inch other) are baseline legal requirements, not winter performance standards. For operations in winter conditions, many fleets and industry sources suggest keeping significantly more tread than the federal floor — figures such as 6/32 inch or more on steer tires and 4/32 inch or more on drives are cited as rough operational targets, not universal rules. Check your fleet policy and applicable state or corridor requirements, which may be more specific.
Practical seasonal planning
- Identify every state in your regular routes and their current seasonal tire rules.
- Check whether your tires carry the required markings (M+S, 3PMSF, or equivalent) for the routes operated.
- Carry chain requirements if operating in chain-law corridors — not all traction alternatives are chain exemptions.
- Review tread depth before winter season, not after the first storm.
- Update the fleet tire spec for winter routes if current tires do not meet requirements.
Size Verification Checklist
- Identify seasonal requirements for all states in the route network.
- Verify tire markings (M+S, 3PMSF) match the applicable requirement.
- Check tread depth before seasonal conditions begin.
- Confirm chain-carrying requirements where chains cannot be substituted.
- Review requirements annually — seasonal rules change.
FAQ
What is the difference between M+S and 3PMSF tire ratings?
M+S (Mud and Snow) is a broad category based on minimum void ratio requirements under ASTM F1805. It is widely available on truck tires and represents a baseline level of mud and snow traction capability. The Three-Peak Mountain Snowflake (3PMSF) symbol indicates that the tire has passed a more rigorous severe-snow braking traction test and provides meaningfully better winter performance. Some jurisdictions that previously accepted M+S have moved toward requiring 3PMSF for chain-law alternatives — always check the current applicable rule.
Are regular highway truck tires acceptable in winter conditions?
Whether a standard highway tire is acceptable depends on the specific state requirements, road conditions, and whether a chain law or traction law is in effect. A tire without M+S or 3PMSF markings may not satisfy winter traction requirements on certain routes even if it is otherwise legal and serviceable. Check both the applicable rules and the tread depth — tires near the federal minimum are unlikely to provide adequate winter traction regardless of their markings.
Can a fleet use chains instead of winter-rated tires?
In many jurisdictions, chains serve as a compliance alternative to winter-rated tires when a chain law is in effect. However, some situations require chains regardless of tire type — for example, some road conditions or chain-control levels may require chains on all vehicles. Whether chains substitute for tire markings or are required in addition depends on the specific rule and the current road condition designation. Check the applicable state DOT requirements for each route.
Source Notes
- Government 49 CFR 393.75 - Tires
- Government TireWise Tire Safety
- Industry U.S. Tire Manufacturers Association Tire Safety
- Site note TruckTireGuide.com editorial notes