Depends on what the course was like and how strong of a runner you are. This spring, I ran 16:24 on the roads, and the very next weekend went 16:00 on the track. Then I went 16:09 on the track and 16:05 on the roads (flat course) the next two weeks. So while that 24-second drop in time could have been attributed to running on the track versus the road, the 16:05 proves that the road didn't slow me down too much in that last race. I would guess that you could run right around 16:00 on the track if the 16:13 was on a fairly quick course, and sub-16 if it was at all hilly or twisty.