Tank Carradine is losing weight to gain more playing time.

After playing primarily inside, Carradine is being moved to the edge of the defensive line, which mirrors the position he played at Florida State.

Carradine, the No. 40 pick in 2013, had 11 sacks in 12 games as a defensive end in his last season with the Seminoles. The 49ers play a 3-4 base defense, but shift to a 4-3 on passing downs.

Carradine presumably is being groomed to serve as a pass-rush specialist, but he must drop weight to have the necessary quickness. Head coach Jim Tomsula said Carradine, who is listed at 295 pounds, is in the 280s and will continue to lose weight. Carradine weighed 276 pounds at the 2013 combine.

“It’s just his skill set,” said Tomsula, who was the defensive line coach in Carradine’s first two seasons. “I’ve gotten more involved in that conversation just because I’ve been with Tank for two years and I see where he’s at.”

Carradine, who didn’t play in 2013 because of a torn ACL he sustained at Florida State, has one sack this season (it came in the opener against Minnesota) and has played more than 19 snaps in two of nine games. He didn’t play in a 17-16 win over the Falcons on Nov. 8.

Carradine has four sacks and 33 tackles in his 17-game career.

Possible suit vs. St. Louis: Running back Reggie Bush said he’s considering suing the city of St. Louis after he suffered a severe knee injury at the Edward Jones Dome in the 49ers’ 27-6 loss to the Rams on Nov. 1.

Bush was injured after he was pushed out of bounds on a punt return. He slipped on a concrete area behind the 49ers’ bench and crashed into a padded wall. Bush, who is on injured reserve, said he sustained a torn meniscus that will require a 4- to 6-month recovery time.

Blue padding has since been placed over the concrete at the Edward Jones Dome. Bush, 30, said he is “looking into some things” before filing a lawsuit.

“I’ve never seen anything like that,” Bush said. “It’s just bizarre.”

On Oct. 25, Cleveland quarterback Josh McCown suffered a shoulder injury when he slipped on the concrete at the stadium.

“To get injured when it’s not between the lines is very irritating,” Bush said.

Bush, who signed a one-year deal in March, said he would like to return to the 49ers in 2016.

Injury report: After Tomsula said Wednesday morning that running back Carlos Hyde would get back on the practice field, Hyde remained sidelined with a foot injury that has forced him to miss the past two games.

Hyde, who reportedly has a stress fracture, hasn’t played since a loss to the Seahawks on Oct. 22. His injury typically requires a 4- to 6-week recovery.

Meanwhile, wide receiver Anquan Boldin was limited with a hamstring injury that has sidelined him for two games.

Eric Branch is a San Francisco Chronicle staff writer.