Phil Brown had said he would be signing "a goalkeeper with potential from a lower league club" to deputise, but has instead moved for 30-year-old Tyler.
The 6ft Norwich-born player will join on a month's loan with a view to a permanent deal.
Tyler was with Norwich City on schoolboy terms before joining Peterborough in 1994, where he made his debut as a 17-year-old. He's spent the whole of his professional career at London Road, except for a loan spell at Yeovil in '96.
He's made over 400 appearances for the club, but has suffered two career-threatening injuries. The first actually happened in a game against Hull City in January 1999 when he punctured a lung. Just over a year later, a wrist injury was discovered, but it was not as serious as first thought.
He has also been involved with the England Under-21s, and was a part of the Toulon tournament winning squad in 1994.
Meanwhile, Damien Delaney is set to seal a move to QPR today. Although the transfer fee is not being officially disclosed, it is thought to be worth £600,000 up front, and potentially double that based on incentives.