An increase in average odometer mileage has pushed used classes 6-7 truck prices lower this year compared to last year to date as prices and volume have fallen from 2013 levels that marked a post-recession high-water mark.

Volume in sales of classes 6-7 recovered in September for the first time in five months, yet still remains lower than most months in 2013, according to ACT Research. Volume has fallen in 2014 in used sales in these classes to 315 units per month. In October, volume rose 1 percent and remains lower than year-ago levels.

At the same time, the average selling price fell sharply in September to $19,658 compared to a year ago. The October selling price "improved dramatically," said Steve Tam, ACT's vice president of the commercial vehicle sector. In October, the average price was $24,862. In May, the average monthly sale price reached an all-time high of $25,564.

"Much like the Class 8 market, scarce inventory and strong demand have conspired to drive prices up in the Classes 6-7 segment," Tam said.

The average mileage for Class 6-7 used sales came in at 221,868 in September. It has remained around the 200,000-level since early 2012. Older units appear to be driving the higher mileage trend. September was the second highest month on six years, as truck age reached 126 months.

By Paul Clinton