The tide

Picture a building with elevators. Where a truck sits inside its floor is spec and mileage: the things a spec sheet shows. Which floor the whole building is on is the market regime, the tide that lifts or lowers every truck regardless of what it is. Since 2021 the tide has moved more than any spec ever could.

In late 2021 the factories could not get parts, freight was booming, and J.D. Power's benchmark sleepers were appreciating 7.1 percent a month at auction. By spring 2024 the same analysts reported that retail prices for model-year 2022 trucks had fallen nearly 26 percent in two months, from 128,768 to 95,365 dollars. Between those points, late-model used trucks roughly doubled and then gave most of it back.

What the tide is made of

Four forces, and the first two do most of the work. New-truck deliveries: every new truck a fleet takes displaces a used one, so factory output six to nine months ago is used supply today. Freight: rates and volumes decide whether carriers have cash to buy and whether the weakest of them hand trucks back to lenders. Interest rates: they set the dealer's floor-plan cost and the owner-operator's monthly payment, which decides how many buyers can afford a 60,000 dollar truck. Diesel: when fuel is dear, newer and more efficient trucks earn a premium.

Behind those sit the slower forces. Regulation raises the price of a new truck and so the ceiling on used ones. California's rules make a pre-2010 engine a different asset in Los Angeles than in Dallas. Exports to Mexico set the floor under the oldest tractors in the border states, and Mexico closed that door to used tractor-trailers in April 2026.

What normal looks like

Normal is about 2 percent a month. J.D. Power called 2.2 percent monthly depreciation for three-to-five-year-old sleepers at retail "historically typical" for 2024. Auction depreciation for four-to-six-year-old sleepers ran 0.8 percent a month in 2024, then 1.8 to 2.2 percent through 2025. In the bad months of 2023, unsold trucks on lots were losing close to 6 percent a month, three times normal.

This month's tide

Two of the four forces moved sharply in September 2026. Diesel reached 6.53 dollars a gallon in the week of 21 September, up 24 cents in a week and 2.78 dollars on the year, according to the Energy Information Administration. That is a fuel shock of the kind that tilts value toward newer, more efficient trucks and squeezes the owner-operators who buy the older ones. And on 16 September the Federal Reserve raised its target range by a quarter point to 3.75 to 4 percent, citing inflation that "remains elevated." Dearer money means a dearer floor plan for the dealer and a bigger monthly payment for the buyer.

Meanwhile the supply side is turning. Sandhills counted heavy-duty inventory down 37.7 percent on the year in August, with auction values up 4.9 percent on the month. ACT Research put the average used class 8 retail price at 60,986 dollars in July, down 4 percent on the month and 2 percent on the year, on sales volumes up 45 percent from a weak July 2025. And J.D. Power's September edition warned that more three-to-five-year-old sleepers will "return on trade" as the backloaded 2027 model year delivers in the fourth quarter. Scarce inventory, dear fuel, dearer money, and a trade-in wave forming: the tide is turning at both ends at once, and which end wins for a given truck depends on its age.

Who the tide hurts

The largest truck dealer in the country. Rush Enterprises' gross margin on used trucks fell from 18.7 percent in 2021 to 9.9 percent in 2022, which its annual report attributed to "declining used commercial vehicle values as new Class 8 vehicle production increased." Nine points of margin on a line of business above 400 million dollars, gone in a year, at the company with the most information in the industry. An independent dealer with one lot has fewer ways to cope, and the same tide.

A monthly book reports the tide after it has turned. The forces that move it are visible weeks earlier, if someone is watching them.