DETROIT — With Chevy Silverado and GMC Sierra pickup trucks piling up on dealer lots, General Motors is offering generous deals to thin the stock.

It’s matching or beating discounts from rivals Ford and Chrysler, offering up to $9,000 off remaining 2012 models and close to $4,500 off 2013s. That, plus low interest rates, sweet lease deals and abundant financing, is good news for people in the market for a truck.

“They’re all very competitive with each other right now,” said Russell Barnett, who owns dealerships around Winchester, Tenn., that sell GM pickups as well as the Ford F-Series and Chrysler’s Ram. “The manufacturers are putting a big emphasis on it, and there’s a lot of people in the market.”

Last month, the Ram led the way with an average of $4,800 in discounts, followed by GMC and Ford at $3,700, according to industry statistics from J.D. Power and Associates. GM dropped incentives on the Silverado to just under $3,700. Dealers say GM has boosted its offers in December, while the others have either held steady or raised incentives on certain models. Barnett said the incentives run from $4,500 to around $5,000, although the discounts vary with model year and options on the trucks.

That means there’s good deals on Ford’s F-Series pickup, the top-selling vehicle in America, as well as the Silverado, which ranks second. Together, the Detroit Three control 83 percent of the U.S. full-size pickup truck market.

The three automakers have been vying for truck business all year as the market continues a slow rebound from the Great Recession. Chrysler led the way on incentives most months, sometimes exceeding $5,000. GM also topped $5,000 earlier in the year. But in November, the company cut discounts on the Silverado and Sierra by about $400, falling almost $1,200 below the Ram and $100 below Ford. The cut came just as the pickup truck rebound accelerated, costing GM sales and forcing it to respond this month.