AUBURN HILLS, MI – Ram refreshes its heavy-duty lineup for 2013, promising best-in-class towing and payload ratings.

The Chrysler brand will unveil its ’13 Ram 2500 and 3500 heavy-duty pickups, along with ‘13 Ram 3500, 4500 and 5500 chassis-cab work trucks on Thursday at the Texas State Fair in Dallas. However, neither Chrysler nor Ram will reveal towing and payload ratings until the North American International Auto Show in Detroit in January.

During a preview here at Chrysler headquarters, journalists are shown exterior and interior refreshes of the ’13 Ram 2500, 3500, 4500 and 5500.

The changes dovetail with Ram’s update of the 1500 light-duty pickup. All trucks in the lineup receive interior upgrades and will feature UConnect, Chrysler’s infotainment system which allows drivers to connect wirelessly to the Internet.

Production begins in January with deliveries launching in March, which Chrysler says is an unusually fast turnaround for a model-year refresh.

“The economy’s starting to come back. We’re starting to see unemployment decline. All of those things will help to drive truck sales,” Ram CEO and President Fred Diaz tells reporters.

Chrysler also will reveal pricing for its heavy-duty pickups at the Detroit show.

For 2013, Chrysler introduces Ram Active Air Induction, an automatic air-intake system that opens an electric valve at high temperatures. Air-intake valves are moved to the front fenders to prevent snow, dirt and other debris from entering the cabin. The technology is standard on all models.

For the first time, Chrysler will offer a gasoline engine on both the Ram 3500 pickup and chassis cab, the 5.7L Hemi. The 3500 previously was available only with a Cummins diesel engine. The 6.7L Cummins diesel carries over from the previous generation, and Chrysler says the engine, mated with an Eisen 6-speed transmission, produces 850 lb.-ft. (1,150 Nm) of torque.

To meet 2013 emissions standards, the auto maker has added diesel exhaust fluids that reduce the amount of pollutants released into the environment and added selective catalytic converters to its powertrains.

While it hasn’t revealed towing rates, the auto maker says heavy-duty Rams now have a 3-link frame suspension up front and a 50 KSI steel suspension in the rear. Trailer hitches are upgraded to Class 5 for the 2500 and 3500 models. To increase payload, high-strength steel frame rails are added and the rear suspension is widened.

Chrysler promises brake life on its heavy-duty trucks is three times longer than that of previous generations. The auto maker also has tweaked the trucks’ hood, grille, running board, bumpers and wheels for a more aerodynamic feel.

Ram will continue offering a manual transmission, noting that its take rate is about 10%. Like the 1500, trims will be offered from the low-end SLT to the topline Laramie Longhorn, but Diaz says most customers are expected to steer toward the brand’s Tradesman line.

afoley@wardsauto.com