Tunks brings a wealth of experience to Prenton Park, after a playing career spanning more than 850 games and spells coaching with Newcastle, Blackburn and England's Under-16 and Under-20 teams.
Tunks told the club's official website: "I'm looking forward to the challenge and am happy to be at Tranmere.
"There is some young talent at the club that needs some help and guidance and I hope I can provide it."
Boss John Barnes added: "I'm pleased Roy has agreed to join us.
"He is an experienced goalkeeper coach who will work with both our first team and youth team goalkeepers and will help them improve their games."