49ers Hold an Offensive Clinic, 55-17 : NFC: San Francisco scores on every possession in the first half and clinches division title with easy victory over Detroit.

This time, the San Francisco 49ers played with an attitude. They wanted to clinch the NFC West long before the fourth quarter. And they did.

The 49ers, after blowing a big chance last week, scored on every possession in the first half behind Steve Young and routed the Detroit Lions, 55-17, Sunday to win their 10th division title in 12 years.

Young, the NFC’s leading passer, threw for 354 yards and four touchdowns in less than three quarters, and left with a 45-10 lead. The 49ers (10-4) went on to score more points in Detroit than any Lions’ opponent ever.

“We lost a tough game last week, and we just wanted to come back strong today,” said Jerry Rice, who caught four passes for 132 yards and one touchdown. “It will be the same for Detroit. They have a great team, and they’ll bounce back from this.”

The Lions (8-6) remain tied with Green Bay for the NFC Central lead.

The 49ers, who did not punt, rolled up 565 yards.

Dexter Carter ended the 49ers’ romp with a 50-yard touchdown run in the closing minutes. Last week in Atlanta, San Francisco missed a chance to clinch the division when Carter fumbled twice, enabling the Falcons to rally from a 24-7 deficit in the fourth quarter for a 27-24 victory.

The 49ers joined Dallas, the New York Giants and Houston as teams that have ensured playoff spots. It was the seventh time this season the 49ers have scored at least 35 points and the fourth time they have exceeded 40 points.

Yet there was no celebrating in the 49ers’ dressing room. They close out the regular season at Candlestick Park, playing host to Houston on Christmas Day and Philadelphia on Jan. 3. Victories in those games would ensure the 49ers home-field advantage in the playoffs.

That’s important, since all four of the 49ers’ losses this season have come on the road.

“We have to forget about this game right now, and start worrying about Houston, because they’ve got a tough team,” said Tom Rathman, who scored two touchdowns.

Young completed 17 of 23 passes before being replaced by Steve Bono with 2:33 remaining in the third quarter. Even with his reduced playing time, Young came within 59 yards of Sonny Jurgensen’s record of 403 yards against the Lions in 1961.

“When the season started, we had a lot of young players and rookie-of-the-year candidates,” Young said. “When we started 3-3, it could have gone either way, but here we are. I don’t think the young guys are playing like rookies any more.”

The 49ers led 31-10 at halftime on touchdown pass plays of 68 yards to John Taylor, 20 yards to Sanjay Beach and 80 yards to Rice, a two-yard touchdown run by Rathman and a 43-yard field goal by Mike Cofer. Three of the scoring drives took less than one minute.

The romp continued as the 49ers opened the third quarter with a 33-yard completion from Young to Rice, setting up a one-yard touchdown dive by Rathman.

Gary Anderson fumbled the ensuing kickoff and Damien Russell recovered for the 49ers. Three plays later, Young completed a 12-yard touchdown pass to Amp Lee.

Erik Kramer, in his second start since taking over at quarterback for the Lions, completed 19 of 29 passes for 220 yards. He had touchdown pass plays of 12 yards to Derrick Moore and 31 yards to Herman Moore.