SANTA CLARA, Calif. — It has been quite an adjustment for Barry Sims since he moved across San Francisco Bay to join the 49ers.

"I'm getting used to wearing red," said Sims, who spent the first nine seasons of his NFL career in Oakland Raiders' silver and black.

Now Sims is playing for his former neighborhood rival, and the change is more than just the uniform on his back.

After starting 119 games for the Raiders, most at offensive left tackle, the 49ers brought in the veteran last month to challenge Jonas Jennings for the starting tackle position on the right side.

It's a good opportunity for Sims, who was released by Oakland on Feb. 26, and a much-needed addition for the 49ers. San Francisco was desperate for veteran help at tackle after former starter Kwame Harris signed with the Raiders earlier this year and Adam Snyder was moved to guard to replace Larry Allen.

Since signing a $36 million deal with the 49ers in 2005, Jennings has missed all or part of 32 games due to injury. Jennings was moved to right tackle this season, flipping sides with second-year player Joe Staley, who established himself as San Francisco's top tackle last year during an auspicious rookie season.

Sims found himself with the first unit at left tackle during Saturday's training camp practice after backup Damane Duckett injured his knee the day before. Staley is out temporarily with an infected toe.

That will be Sims' role with his new team, filling in on both sides of the line while also pushing Jennings for a starting role.

"I'm just helping out where I can right now," Sims said. "I signed here basically to have the opportunity to compete for playing time and get on the field. I've started nine years in this league and I intend to keep on pushing."

Sims soon will be pushing against his former teammates. The 49ers will travel on Aug. 4 to practice for a day against the Raiders at Oakland's summer facility in Napa. The 49ers and Raiders then begin the exhibition season with an Aug. 8 game in Oakland.

"It's funny," Sims said. "I finally get out of Oakland and I still have to go up to Napa. That will be interesting."