Idaho lawmakers are moving forward with a bill that would end the state’s split speed limit for large commercial trucks and set the same maximum speed for heavy trucks and passenger vehicles.
House Bill 664 would amend Idaho law so that vehicles with five or more axles operating at a gross weight of more than 26,000 pounds would be allowed to travel at the same posted speed limits as other motor vehicles. Under current Idaho law, those heavier vehicles must generally operate at lower maximum speeds than lighter vehicles, including a cap that keeps them 10 mph below passenger vehicle limits in certain areas and a 65 mph cap on urban interstates.
For truck drivers, the bill would mark a major change in how Idaho handles speed limits on interstates and state highways. Supporters argue the current speed gap creates dangerous interactions between faster-moving cars and slower-moving semis, especially when trucks need to pass or move left in heavy traffic. They say reducing the speed differential would improve traffic flow and cut down on sudden lane conflicts.
The bill’s language would replace the current lower-speed rule for heavy trucks with a standard that makes their maximum lawful speed the same as for lighter vehicles. The proposal also includes an emergency clause and says the change would take effect July 1, 2026, if it becomes law.
As of mid-March, the bill had already passed the Idaho House on a 57-11-2 vote. It then advanced through the Senate Transportation Committee and was filed for third reading in the Senate, putting it one step closer to a full Senate vote.
The measure has drawn attention across the trucking industry because Idaho is one of the states that still uses different speed limits for trucks and passenger vehicles. Supporters of the bill have pointed to neighboring states that do not use a split-speed system and argue that consistency is safer than forcing trucks to run slower than surrounding traffic.
Not everyone agrees. The Idaho Trucking Association has cautioned that the bill may not solve the problems lawmakers want to address. The group has said many trucks are already governed below current speed limits and that higher posted limits would not necessarily change real-world truck speeds. The association also raised concerns tied to Idaho’s heavier permitted truck weights and said left-lane restrictions might be a better solution than eliminating split speeds outright.
For the trucking industry, the bill is worth watching because it could change how drivers move through Idaho’s highest-speed corridors. If approved by the Senate and signed into law, the measure would remove one of the more notable truck-car speed differentials still on the books in the West.
House Bill 664 would amend Idaho law so that vehicles with five or more axles operating at a gross weight of more than 26,000 pounds would be allowed to travel at the same posted speed limits as other motor vehicles. Under current Idaho law, those heavier vehicles must generally operate at lower maximum speeds than lighter vehicles, including a cap that keeps them 10 mph below passenger vehicle limits in certain areas and a 65 mph cap on urban interstates.
For truck drivers, the bill would mark a major change in how Idaho handles speed limits on interstates and state highways. Supporters argue the current speed gap creates dangerous interactions between faster-moving cars and slower-moving semis, especially when trucks need to pass or move left in heavy traffic. They say reducing the speed differential would improve traffic flow and cut down on sudden lane conflicts.
The bill’s language would replace the current lower-speed rule for heavy trucks with a standard that makes their maximum lawful speed the same as for lighter vehicles. The proposal also includes an emergency clause and says the change would take effect July 1, 2026, if it becomes law.
As of mid-March, the bill had already passed the Idaho House on a 57-11-2 vote. It then advanced through the Senate Transportation Committee and was filed for third reading in the Senate, putting it one step closer to a full Senate vote.
The measure has drawn attention across the trucking industry because Idaho is one of the states that still uses different speed limits for trucks and passenger vehicles. Supporters of the bill have pointed to neighboring states that do not use a split-speed system and argue that consistency is safer than forcing trucks to run slower than surrounding traffic.
Not everyone agrees. The Idaho Trucking Association has cautioned that the bill may not solve the problems lawmakers want to address. The group has said many trucks are already governed below current speed limits and that higher posted limits would not necessarily change real-world truck speeds. The association also raised concerns tied to Idaho’s heavier permitted truck weights and said left-lane restrictions might be a better solution than eliminating split speeds outright.
For the trucking industry, the bill is worth watching because it could change how drivers move through Idaho’s highest-speed corridors. If approved by the Senate and signed into law, the measure would remove one of the more notable truck-car speed differentials still on the books in the West.
