California Allows Studded Tires From November 1 to April 30

The starting point in section 27454 is a flat prohibition. A tire on a vehicle upon a highway "shall not have on its periphery any block, stud, flange, cleat, ridge, bead, or any other protuberance of metal or wood that projects beyond the tread of the traction surface of the tire." Everything California allows is an exception written into that section, and each exception carries its own numeric limit. The section was last amended by Stats. 2008, Ch. 220, effective January 1, 2009.

The studded-tire exception is subdivision (e)(1). It permits pneumatic tires containing metal-type studs of tungsten carbide or other suitable material, inserted or constructed so that under no condition will the number of studs or the percentage of metal in contact with the roadway exceed 3 percent of the total tire area in contact with the roadway, and only "between November 1 and April 30 of each year." The same paragraph adds a year-round alternative: a vehicle may run tires whose studs retract pneumatically or mechanically when not in use, provided the studs are retracted between May 1 and October 31. There is a wear rule attached to that alternative, and it is easy to miss: a tire "shall not be worn to a point at which the studs protrude beyond the tire tread when retracted." A worn retractable-stud tire stops qualifying in summer even though the mechanism still works.

The season can be lengthened but not shortened. Subdivision (e)(2) lets the commissioner of the California Highway Patrol, after consultation with the Department of Transportation, extend the period during which studs may be deployed "in areas of the state for the protection of the public because of adverse weather conditions." That is a targeted power keyed to an area and to weather, so a Sierra pass can be running on extended stud authority in May while the rest of California is back under the April 30 cutoff. Authorized emergency vehicles are outside the calendar entirely: subdivision (f) gives vehicles defined in section 165 the unrestricted use of studded pneumatic tires throughout the year, still subject to the same 3 percent metal-contact cap.

Three further exceptions in section 27454 catch equipment people often assume is banned. Subdivision (b) allows pneumatic tires with wire embedded in them, provided the wire does not exceed 0.075 of an inch in diameter and the metal in contact with the roadway never exceeds 5 percent of the tire area in contact with the roadway, except that during the first 1,000 miles of use the metal may exceed 5 percent but must never exceed 20 percent. Subdivision (c) exempts vehicles operated on unimproved roadways when necessary in the construction or repair of highways. Subdivision (d) exempts traction engines and tractors operated under a permit first obtained from the Department of Transportation. Subdivision (a) is the everyday one: tire traction devices of reasonable size used to prevent skidding on wet surfaces or on snow or ice.

Chain controls are governed by a different section and answer a different question. Section 27459 says no person shall operate a motor vehicle, trailer or semitrailer on a portion of highway "without tire traction devices when that portion of the highway is signed for the requirement of tire traction devices." For a passenger vehicle or motortruck with an unladen weight of 6,000 pounds or less, the devices go on at least two drive wheels, and Caltrans or the local authority may provide in the alternative that snow-tread tires on at least two drive wheels are acceptable when weather and surface conditions make their stopping, tractive and cornering abilities adequate. Those tires must be in good condition and bear the marking M-S, M/S or an equivalent snow marking; tires bought before January 1, 1987 may instead satisfy the tread pattern requirements of section 558. Section 605 defines tire traction devices and requires each one to carry, at manufacture or final assembly, a permanent impression of the assembler or primary manufacturer name, initials or trademark and the country of manufacture.

None of this varies by city. Vehicle Code section 21 makes the code "applicable and uniform throughout the state and in all counties and municipalities therein" and bars a local authority from enacting or enforcing an ordinance on matters covered by the code unless expressly authorized. A mountain city cannot lengthen the stud season on its own streets, and a valley city cannot shorten it. What a local authority can do is post a traction-device requirement on a road it controls, which section 27459 expressly contemplates.

A tire that violates section 27454 is an equipment violation. 1 makes it "unlawful and constitutes an infraction for any person to violate, or fail to comply with any provision of this code," so running studs on May 2 or an over-limit stud pattern in January is an infraction, not a misdemeanor. Section 42001(a) sets the base fine at not more than $100 for a first infraction, not more than $200 for a second within one year of a prior conviction, and not more than $250 for a third or subsequent infraction within one year of two or more prior convictions, before penalty assessments.

Driving past a posted chain-control sign without tire traction devices is a separate infraction under section 27459 and is enforced at the control point itself by California Highway Patrol officers and Caltrans-directed checkpoints on state highways, and by the local agency on roads it controls. Where an officer writes an equipment citation as a notice to correct violation under Vehicle Code Article 4, commencing with section 40610, section 40611 requires the court clerk to collect a $25 transaction fee for each violation upon proof of correction, and imposes no fee at all if the violation notice is processed only by the issuing agency with no record transmitted to the court.