Bell injured his knee in Sunday’s win over the Cincinnati Bengals and is doubtful for the wild card clash with Baltimore Ravens, although he has not sustained any serious ligament damage.
Tate has had spells with the??Cleveland Browns and Minnesota Vikings this season after previously playing for the Houston Texans, who signed him as a second-round draft pick in 2010.
The 26-year-old has a career total of 540 carries for 2,363 yards and 14 rushing touchdowns while adding 67 catches for 347 yards from his 51 NFL games.
Pittsburgh have released wide receiver Justin Brown in order to make room for Tate on their roster.