Substitute Tuncay's first goal for the club secure a precious point for Middlesbrough and left Reading looking anxiously over their shoulders heading into crucial Christmas period.
The Turkish striker came off the bench to rescue Boro seven minutes from time after Dave Kitson had fired Reading in front nine minutes into the second half.
An insipid first half had seen Reading take the best part of 15 minutes to test Ross Turnbull, Boro's third-choice keeper who was making only his fourth appearance because of injuries to Mark Schwarzer and Brad Jones.
Turnbull comfortably kept out Bobby Convey's half-hit shot and reacted well to hang on a sweet shot on the turn from Kitson.
But the visitors had chances on the break in a scruffy game and Reading could consider themselves lucky to be on level terms at the break.
George Boateng had the ball in the net but was clearly offside and Adam Johnson shot through Marcus Hahnemann's legs and onto a post after the Reading keeper had palmed away a Jeremie Aliadiere shot.
But it was Reading who broke the deadlock in an improved second half as Kitson added a touch of class to a poor quality game.
The approach was route one as Hahnemann's free-kick from deep inside the Reading half was flicked on by Kevin Doyle into the path of Kitson, who neatly lobbed the ball into an unguarded net as Turnbull raced into no-man's land.
Doyle saw a shot pushed round the post by Turnbull as Reading looked to kill the game off, but the one goal looked as if it would be enough as Boro offered little cutting edge going forward.
Yet the outcome of the game ultimately hinged on two substitutions as Reading tried to shore the game up by bringing on defender Andre Bikey for winger Convey.
The move seemed to confuse the home side and instead it was Boro sub Tuncay who snatched a point for the visitors.
Luke Young worked hard to find space down the right and his fierce cross was headed home clinically from close range by the onrushing Tuncay.
Reading attempted to repair the damage by bringing striker Shane Long on for midfielder Bryn Gunnarsson and the Royals almost snatched victory late on when Nicky Shorey's superb left-wing cross was headed narrowly off target by the impressive Kitson.
But the reaction came too late and the 1-1 scoreline was ultimately a result that does little to suggest both these sides won't be involved in a relegation scrap this season.