U.S. sales of medium- and heavy-duty trucks surged 18.5% on a daily basis to 33,808 units in June, compared with 30,913 in like-2013, propelled by strong gains in four of the sector’s five classes.

Class 8 sales jumped 31.8% on volume of 19,373 units, compared with 15,929 in the same period year-ago. Daimler led the heavy-duty group with deliveries rising 30.1% to 7,378 from 6,143, but the truck maker’s share-of-segment dipped to 38.1% from 38.6% in like-2013.

Volvo Truck appears to have grabbed the difference, as its share rose to 21.2% of the segment from 19.5% on the strength of a 43.3% sales hike on volume of 4,113 units vs. 3,110 year-ago. All four volume sellers in Class 8 delivered major year-over-year gains.

Class 7 deliveries improved 21.6% to 4,373 from 3,896. Daimler set the pace, using its Freightliner brand exclusively to book a 21.9% sales uptick on volume of 2,002 units. International posted an impressive month, as well, with sales up 22.4% to 1,137.

Class 6 sales fell 15.2% to 3,667, representing the sole loser among the classes. Daimler sales tumbled 36.9% to 1,209, while International deliveries were off 33.3% to 656. Ford was the big gainer in Class 6, with sales up 8.0% to 1,037.

Class 5 sales edged up 1.4% to an even 5,000 units. Ford led the group on volume of 3,018 trucks, but overall sales for the Blue Oval dropped 16.0%. Chrysler made the greatest strides, as deliveries rose 49.1% to 761 copies.

Class 4 sellers witnessed a 42.0% leap on volume of 1,395. Isuzu’s imported builds yielded the greatest demand, up 83.4% to 611.

Total medium-duty sales rose 4.4% to 14,435 from 14,984.

Heavy-duty inventories finished the month at 37,383 units and a days’ supply of 46 compared with 56 in like-2013.

Medium-duty stocks stood at 49,180 and days’ supply of 82, compared with 67 days’ last year. Class 5 carried the most inventory at 94 days’ and 19,580 units.