Retail sales of medium and heavy trucks were up slightly in May, although the year-to-date total continues to lag due to the weaker Class 8 market, according to figures compiled by WardsAuto.

Dealers sold 60,962 trucks with gross vehicle weight ratings above 10,000 pounds in May, up 4% from April and up 5% from a year ago. Big trucks bounced back from declines in April with double-digit gains in May, as Class 7 sales improved 11% and Class 8 improved 17%.

Class 6 sales, however, fell off by 13% to offset some of those gains.

Otherwise, medium-duty truck sales results were mixed: Class 3 saw a 1% month-to-month decline in May, while Class 4 sales were up 5% and Class 5 sales were up 4%.

For the first five months of 2017, medium and heavy truck sales are down 1% compared with the same period last year. A 22% decline in Class 8 canceled out solid gains posted by Class 3 and 4 models, up 14% and 13% respectively.