Coming off their dominating home win over the Titans, the Bengals flew to Heinz Field for a Week 13 AFC North rematch with the Pittsburgh Steelers.  In the first quarter, Cincinnati took the early lead as RB Rudi Johnson got a 1-yard TD run for the only score of the period.  However, in the second quarter, the Steelers took the lead as QB Ben Roethlisberger got a 6-yard TD run, along with kicker Jeff Reed getting a 21-yard field goal.  Pittsburgh would end the half as Roethlisberger completed a 2-yard TD pass to WR Hines Ward.  In the third quarter, the Bengals tried to get back into the game as kicker Shayne Graham nailed a 24-yard TD pass, yet Pittsburgh replied with Roethlisberger and Ward hooking up with each other again on an 8-yard TD pass. For QB Carson Palmer, one week after completing a career-best 84.2% of his passes against Tennessee, he would end this game completing a career-worst 38.6% of his passes.
Question: How many yards was the longest touchdown run?
Answer: 6