Heavy commercial trucks will be allowed to travel at 80 miles per hour on select Idaho interstate highway sections beginning July 1, under a new state law signed earlier this year. The change eliminates a longstanding speed differential between passenger cars and large trucks — a policy that has drawn both legislative support and serious pushback from the trucking industry in Kootenai County and across North Idaho and the Treasure Valley.
Background: Decades of Split Speed Limits
Idaho has maintained different speed limits for heavy trucks and passenger vehicles since the late 1990s. When the split limits took effect, commercial trucks weighing more than 26,000 pounds were capped at 65 mph — a full 10 mph below passenger cars on some rural interstates. That gap narrowed somewhat over the years, with trucks eventually allowed up to 70 mph on certain rural stretches while cars were permitted 80 mph.
Rep. Doug Pickett (R-Oakley) introduced the bill to eliminate that differential in late February, with a House Transportation Committee hearing on Feb. 26. Gov. Brad Little signed the measure into law on March 23. The Idaho Transportation Department board followed with its own authorization of the uniform 80 mph limit in a close vote, clearing the path for the July 1 effective date.
Pickett argued that slower-moving trucks create dangerous situations on high-speed highways. He pointed to a University of Arkansas study from 2005 that found vehicles traveling 10 mph below posted speeds experienced a 227% higher frequency of traffic interactions — the kind that lead to collisions. “Speed doesn’t kill. Differential speed kills,” Pickett said.
He also estimated Idaho is one of 10 or fewer states that still maintain differential speed limits for commercial trucks.
Where the New Limit Applies
The uniform 80 mph limit will apply to specific interstate sections rather than all of Idaho’s highway network. Affected roads include segments of I-84 west of Caldwell and east of Boise in the Treasure Valley, along with portions of I-86 and I-15 further east. Drivers traveling between Kootenai County and the Treasure Valley on I-84 could encounter the new conditions as they move through those corridors.
For more on how road construction is currently affecting travel times in the region, see the latest updates on summer construction on Seltice Way in Post Falls, where westbound lanes remain closed through August.
Trucking Industry Raises Safety Concerns
Despite the legislative push, the commercial trucking industry is far from enthusiastic about the change. Allen Hodges, president of the Idaho Trucking Association, said plainly: “We have grave safety concerns.”
Those concerns center on the physical realities of large commercial vehicles. The association has cited Idaho Transportation Department data suggesting crashes between commercial trucks and passenger cars on higher-speed highways result in more fatalities and injuries. Trucking representatives also point to a significant mechanical limitation: most commercial truck tires are only rated for speeds up to 75 mph — meaning the new 80 mph limit would technically push trucks beyond their tires’ design specifications.
Stopping distance is another issue. At 80 mph, the heaviest commercial trucks require an additional 200 feet of braking distance compared to lighter vehicles. Given that Idaho is one of only two states the federal government authorizes to carry loads up to 129,000 pounds daily — far exceeding the 80,000-pound weight of most commercial trucks — that stopping distance concern carries added weight on Idaho roads.
The industry’s own membership data underscores just how skeptical truckers are of the new policy: more than 70% of Idaho Trucking Association members say they have no intention of increasing their speeds under the new law, even though they will now be legally permitted to do so.
What Comes Next for Idaho Drivers and Truckers
The law takes effect July 1, and motorists across North Idaho, the Panhandle, and the broader state should be aware that large commercial trucks may be traveling faster on affected interstate sections this summer. Whether truckers actually increase their speeds remains to be seen — but the legal framework will change regardless.
The Idaho Transportation Department will be responsible for implementing and monitoring the new uniform speed limit. Drivers sharing the road with commercial trucks, especially on rural interstates, should stay alert to changing traffic patterns. Travelers heading south from Coeur d’Alene and Post Falls toward the Treasure Valley may encounter the new conditions once they reach the affected I-84 corridor.
For statewide transportation and infrastructure coverage, Idaho News at idahonews.co continues to track legislative and transportation developments affecting communities across the state.