UPDATE 3-J.B. Hunt, Wal-Mart climb aboard Tesla's electric truck

(Adds Walmart plans to test Tesla trucks.)

Nov 17 (Reuters) - Wal-Mart Stores Inc and big truck fleet operator J.B. Hunt Transport Services Inc said on Friday they will order Tesla Inc's electric semi trucks, boosting the Silicon Valley automaker's effort to expand its reach beyond luxury cars and solar energy systems.

Walmart plans to order a total of 15 Tesla trucks, five for the United States and ten for Canada.

"We believe we can learn how this technology performs within our supply chain, as well as how it could help us meet some of our long-term sustainability goals, such as lowering emissions, the retailer said in a statement.

Separately, J.B. Hunt was the first major U.S. trucking company to announce an order for Tesla's new "Semi" electric trucks, saying it had reserved multiple vehicles for use on the U.S. West Coast.

Hunt did not say how many of the vehicles it would reserve. Tesla unveiled the Semi on Thursday without specifying prices.

Hunt's statement followed a rejection of the new vehicles on Thursday by Old Dominion Freight Line Inc, the United States' fourth-largest less-than-truckload carrier. Other carriers were also cautious.

"Carriers have been skeptical about the heavy-duty tractor applicability to their models, given questions regarding torque, total hauling capacity, and recharging infrastructure," said Benjamin Hartford, a sector analyst with brokerage Baird.

"(J.B. Hunt is) the first mover, particularly with regard to Tesla, but we expect other carriers to follow as electric tractor viability becomes proven."

Shares of J.B. Hunt were down 1.8 percent while Tesla shares were up 1.2 percent in midday trading.

Tesla has been trying to convince the trucking community that it can build an affordable electric big rig with the range and cargo capacity to compete with relatively low-cost, time-tested diesel trucks.

In a showy launch on Thursday, Tesla chief Elon Musk said the truck could go up to 500 miles (800 km) at maximum weight at highway speed, allowing it to drive from Los Angeles to San Francisco and back without recharging.

Diesel trucks are capable of traveling up to 1,000 miles (1,600 km) on a single tank of fuel.

Tesla showed off the semi on a webcast which offered reservations for the truck at $5,000 each, but Musk did not discuss reservation volume.

A spokesman for United Parcel Service Inc said the courier had nothing to announce regarding Tesla's vehicles but would always look for options that fit its needs.

Brad Pinchuk, chief executive of Dubuque, Iowa-based Hirschbach Motor Lines, said his firm was looking to test non-diesel big-rig options but needed longer ranges than Tesla could provide and speedier fuel-up times.

Pinchuk said he plans to buy two hydrogen-powered trucks made by Salt Lake City-based electric Nikola Motor Company when they are available in 2020.

"Its a different application putting liquid hydrogen into tanks so it will be very similar sort of situation to diesel," Pinchuk said. "Youd be able to fuel up. It would take about the same amount of time to fuel up a diesel and go about the same distance."

(Reporting by Sonam Rai and Arjun Panchadar in Bengaluru, Nandita Bose in Chicago; Editing by Anil D'Silva and Nick Zieminski)