Clare joined from Castleford on a deal until the end of 2016, while Ryan has signed on until the end of the current campaign.
“Both have good Super League experience and I think that is going to be important heading into the Super 8s,” Lowes told his club’s official website.
“James is a young lad, who is going to have a long future in the game.
“He is a finisher with great pace and when he became available, we grabbed him.
“Matt had a great season with Wakefield last year and has got a few Super League games under his belt.
“He offers us fantastic cover, both in the back-row and in the centres.
“You want competition for places and they should certainly lift what we are doing in training.”