California’s 55 mph Truck Limit and Right-Lane Rules
A navigation app may show 65 or 70 mph on a California freeway while roadside signs say “TRUCKS 3 AXLES OR MORE 55” or “TRUCKS USE RIGHT LANE.” Choose speed and lane from the actual vehicle configuration and the signs. The 55 mph maximum applies to particular vehicles. Lane use also depends on posted designations and how many lanes run in your direction.
Which vehicles are limited to 55 mph?
For freight drivers, two situations in California Vehicle Code § 22406 are especially common. The first is a motortruck or truck tractor with three or more axles. Its maximum highway speed is 55 mph.
The second is a motortruck or truck tractor drawing another vehicle. Axle count does not control this provision. A two-axle truck towing a trailer can therefore be subject to the 55 mph limit.
The section also covers a passenger vehicle or bus drawing another vehicle, a school bus carrying pupils, a farm labor vehicle carrying passengers, a vehicle transporting explosives and a trailer bus. These are distinct categories even though most ordinary freight carriers will rarely encounter them.
A two-axle straight truck without a trailer does not fall under § 22406(a) simply because it has commercial plates, a USDOT number or a CDL driver. Hitching a trailer changes the analysis. Check actual axles, towing status and vehicle category rather than relying on the label “commercial truck.”
Reduce speed when conditions call for it
Even if the general posted limit is 65 or 70 mph, a vehicle covered by § 22406 cannot exceed 55 mph. Obey a lower posted limit. Under California Vehicle Code § 22350, adjust to weather, visibility, traffic, surface and road width. Slow further when conditions require it, even without another speed sign.
A closely following car does not raise the legal maximum. Section 22400 prohibits unjustifiably slow driving that impedes normal traffic, but allows slowing for safety, grade or compliance with law. Do not exceed 55 mph to keep pace with passenger cars.
Start with the posted lane designation
Follow “TRUCKS USE RIGHT LANE” and other truck lane signs. Caltrans may designate one or more lanes for vehicles subject to § 22406 or designate a reduced-speed lane. The location need not be the same along every stretch. The Caltrans truck lane use page collects the relevant provisions. On the road, use the regulatory signs and lane markings in front of you.
Without a designated lane, normally use the rightmost traffic lane
Where no lane is designated, § 21655 and § 22348(c) generally require these vehicles to use the right-hand lane for traffic. That means the rightmost normal traffic lane in your direction, not the shoulder.
Count four lanes in one direction
On a divided highway with no designated lane, if four or more lanes are clearly marked in the same direction, the restricted vehicle may use the right-hand lane or the lane immediately to its left. Count lanes in your direction only, not the two directions combined.
Even with five or six lanes in one direction, this generally means the two farthest right, not any two you choose. With two or three lanes in the same direction, normally cruise in the rightmost lane. The adjacent lane to its left may be used for passing, not for continuous ordinary cruising.
Stay within the passing allowance
To pass slower traffic, a restricted truck may use the lane immediately left of the rightmost lane. Where lanes are designated, stay within what signs and law allow. Passing generally does not authorize moving into a third lane or farther left. The 55 mph maximum still applies while passing. Return to an allowed lane when safe.
Use the lanes needed for exits, entrances and interchange splits
Allowances exist for turning, entering or leaving a freeway and following an interchange split. If the vehicle needs another lane to stay on its intended route, follow the posted directions. For example, when a route branches from a left lane, use that lane rather than missing the route to stay on the far right.
The move is for the immediate entrance, exit or split. Congestion is not a reason to remain farther left. Beyond the split, check the signs and lane count again and return to a lane allowed on that stretch.
A truck outside the 55 mph category may still have to keep right
A two-axle truck that is not towing may be outside § 22406(a), but the slower-traffic keep-right rule in § 21654 may still apply when traveling below the normal speed of traffic in the same direction. The provision makes exceptions for passing or preparing to turn left.
A two-lane highway carrying traffic in opposite directions has its own rule. If passing is unsafe and five or more vehicles are lined up behind a slower vehicle, § 21656 requires the driver to turn off at the nearest turnout and let them pass. If no marked turnout is nearby, use a place wide enough to turn off safely. This is separate from the right-lane rule on a multilane freeway.
Truck-only lanes have their own facilities and signs
A truck-only lane separates trucks from mixed-flow traffic. An ordinary rightmost lane is still a general traffic lane. At the article’s review date, the Caltrans truck-only lanes page listed two facilities, at the I-5/SR-14 split in Los Angeles County and at the southbound I-5/SR-99 merge near Grapevine in Kern County. Black-and-white signs direct trucks into these facilities.
A decision sequence on the road
1. Check the vehicle. Count axles, identify anything being towed and check whether another category in § 22406 applies.
2. Check speed. Read the posted limit. If § 22406 applies, stay at or below 55 mph. Slow further for a lower sign or unsafe conditions.
3. Check lanes. Look for designated truck or reduced-speed lanes first. If none is posted, count the lanes in your direction.
4. Identify the maneuver. Cruising, passing, taking an exit and following an interchange split do not all permit the same lane use.
Navigation helps plan the route but cannot replace the signs and markings at the scene. For a citation or lane dispute, preserve the location, direction, vehicle combination, signs, lane count and maneuver underway. Have fleet safety staff or a qualified professional assess the original records.
Disclaimer. This article draws on the California Vehicle Code, Caltrans and California DMV public information as of August 31, 2026. It provides general information, not legal advice, a driving qualification decision, a traffic citation defense or other individual professional advice. Speed and lane requirements, signs, road geometry, enforcement and penalties depend on the vehicle combination, location, controls and facts. Use current law, signs, markings, officers’ directions and official records. This article does not determine how a rule, road segment or citation applies for a driver, fleet, enforcement agency or court. Consult fleet safety staff, qualified counsel or the responsible agency about citations, crashes or significant liability. The author and publisher accept no liability for losses arising from actions taken on the basis of this article.
California Legislature. “California Vehicle Code § 21654.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=21654. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 21655.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=21655. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 21656.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=21656. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 22348.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=22348. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 22350.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=22350. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 22400.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=22400. Accessed 31 Aug. 2026.
California Legislature. “California Vehicle Code § 22406.” California Legislative Information, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=22406. Accessed 31 Aug. 2026.
California Department of Motor Vehicles. “Section 7: Laws and Rules of the Road (Continued).” California Driver’s Handbook, https://www.dmv.ca.gov/portal/handbook/california-driver-handbook/laws-and-rules-of-the-road-cont1/. Accessed 31 Aug. 2026.
California Department of Transportation. “Truck Lane Use.” Caltrans, https://dot.ca.gov/programs/traffic-operations/legal-truck-access/truck-lane-use. Accessed 31 Aug. 2026.
California Department of Transportation. “Truck-Only Lanes.” Caltrans, https://dot.ca.gov/programs/traffic-operations/legal-truck-access/truck-only-lanes. Accessed 31 Aug. 2026.