Nick Bunkley 

DETROIT — It’s been three consecutive months of bronze for the Chevrolet Silverado.

After managing another second-place upset in May, Fiat Chrysler’s Ram is threatening to upend the all-important but usually predictable pickup battle. A year ago, Chevy launched a brazen marketing assault on the long-dominant Ford F series, with a series of commercials asserting that its new aluminum body was too fragile to survive a day at the job site unscathed.

Now, with Ford already opening up a 139,000-unit edge over the Silverado on the year and the Ram on pace for its first half-million sales year ever, Chevy looks to be the more vulnerable one. Going into this year, the Ram had only beaten the Silverado in two prior months, largely due to fluky timing.

“That’s a big crown to wear, to say you beat Silverado, and to see it happen month after month — it’s exciting. We’re enjoying it,” said Joshua Wischnewsky, general manager of Bayshore Chrysler-Jeep-Dodge-Ram in Baytown, Texas. “We have had probably our three biggest months of Ram trucks in the history of the store.”

Five months into 2017, the Silverado leads the Ram by 5,055 units, thanks to a big cushion Chevy built up in February. But that’s less than one-sixth the margin it had at this point in 2016.

General Motors spokesman Jim Cain noted that GM splits full-size pickup sales with a second nameplate, the more upscale GMC Sierra. GM also sells two midsize pickups, the Chevy Colorado and GMC Canyon, which have no direct domestic competition until the Ford Ranger returns in 2019.

“One should never discount the contribution of GMC to our pickup strategy,” Cain said. “It’s a high-volume, premium brand and it makes a monthly comparison to Silverado alone kind of unfair. It’s like we’re playing with one hand tied behind our back with that analysis.”

Cain said GM has been intentionally less aggressive on pickups, reducing discounts in anticipation of more demand in the second half of the year. Ram, though, is offering significantly higher incentives than Chevy and Ford, though that’s not unusual. But FCA has been giving dealerships more reason to push Ram sales by emphasizing it in monthly stair-step targets.

Meanwhile, May marked Ford’s third straight month selling more than 70,000 F-series pickups, the automaker’s longest such streak since 2005. The F series has outsold the combined total of GM’s four pickup nameplates in each of the past three months, putting Ford on track to be the nation’s top pickup brand for the first time since 2014.

Chevy changed its discounting strategy for June, eliminating a “bonus tag” promotion that had been running since last summer and instead offering uniform 17 percent discounts on all light-duty Silverado LT models. (Buyers also can choose no-interest, 60-month loans.) The discounts would amount to roughly $8,200 on a $48,000 Silverado 1500 crew cab, compared with incentives of up to $10,500 on a comparable Ram in some markets and up to $7,050 on a similarly equipped F series, according to examples provided by Cox Automotive.

“We feel really good about our go-to-market strategy in June, and it should be a nice way to start a summer and fall selling season where you naturally see a rotation into pickup trucks,” Cain said. “We should do very well with pickups” in the second half of the year.

Ford will be amping up the pressure with a freshened F-150 on the way this fall, and Ram will follow that with a redesign early next year. GM has full redesigns of the Silverado and Sierra on the way, but they’re not expected until the latter part of 2018.

Pickups were one of the U.S. industry’s best-performing segments in May, with sales up 9.3 percent. Sales of all other light trucks rose 6.2 percent, but a 10 percent drop in car sales pushed the industry down 0.5 percent overall, the fifth consecutive monthly decline.

Many analysts have recently pulled back on their full-year forecasts and now project 2017 sales to come in about 2 percent below last year’s record of 17.55 million.

The industry’s seasonally adjusted, annualized selling rate fell to 16.7 million in May, the third month in a row with a rate less than 17 million.