DETROIT (Reuters) - Specialty truckmaker Oshkosh Corp (OSK.N) reported stronger-than-expected earnings on Tuesday as strong sales of tactical vehicles to the Pentagon helped offset continuing weakness in construction equipment sales.

It also predicted the coming year would be "solidly profitable," helping send the company's shares higher in premarket trading.

Oshkosh, which makes fire trucks, concrete mixers and military vehicles, reported a fiscal fourth-quarter net profit of $140.3 million, or $1.68 a share, up from $53.7 million, or 72 cents a share, last year.

Earnings from continuing operations fell to $52.4 million, or 63 cents per share, from $62.4 million, or 84 cents a share.

Excluding tax and inventory benefits and $1.05 per share from discontinued operations, Thomson Reuters I/B/E/S said the company earned 27 cents per share, beating analysts' average forecast for 16 cents.

Sales fell 20 percent to $1.49 billion.

The company also said it expected to be "solidly profitable in fiscal 2010," as the continued strength in its defense business would "more than offset anticipated low demand at our construction-related businesses."

In the quarter just ended, defense segment sales rose 54.6 percent to $855.4 million. That helped offset a 58.2 percent decline in sales of access equipment like telehandlers, a 40.4 decline in sales of concrete mixers and a 16.7 percent decline in fire and emergency vehicles.

The shares were last up at $33.05 in premarket trading after closing Monday at $31.83 on the New York Stock Exchange.

(Reporting by James Kelleher and Christopher Kaufman; editing by John Wallace, Dave Zimmerman)