Charles suffered a bruised thigh during last week's 28-2 win over the Jacksonville Jaguars and only took part in limited training with the team today.
However, Reid insists that the training decision was merely a precaution and hopes that the 26-year-old will be ready to play at the weekend.
"He did the walkthrough this morning. He might do a little bit this afternoon. We're just taking it slow. I think he'll be OK for the game. We'll see how it all works out," Reid told reporters.
Charles returned from an ACL injury in 2011 to rush for 1,509 yards last season, earning himself a place in the Pro Bowl.