Schneider National said it has started selling its used fleet trucks that have just come off the road, most in the 2005 through 2007 model years.

Used heavy-duty truck prices softened in October at the same time the average mileage of used tractors climbed to an all-time high, ACT Research said last week.

Used truck prices continued to rise in August while low-mileage inventory remained scarce at many dealerships, according to ACT Research and American Truck Dealers.

With low-mileage used Class 8 trucks increasingly difficult to find, sales declined in July, ACT Research and dealers said.

Used truck prices declined in June from the previous month, as sales slowed and more inventory became available, according to ACT Research and several dealers.

Rising prices for older-model used trucks have forced sellers to come up with new approaches to make tractors more affordable, according to industry executives.

The increase in new Class 8 deliveries in 2011 hasn’t yet done anything to ease the scarcity of used vehicles and, if anything, has added even more upward price pressure, industry executives and analysts said.

Registrations of used trucks barely increased in the first nine months of this year, while tight supplies of them forced buyers to pay 19% more than they did last year for trucks with higher mileage, according to market researchers.

The scarcity of low-mileage used Class 8 trucks has gotten worse, pushing prices nearly 25% higher than what comparable vehicles cost last year, dealers and market analysts said.

Sales of used Class 8 trucks fell 20.4% in May from the same month last year, while prices jumped 5% from April, because of low inventories, numerous sources said.