Your road bike is going to be harder to make work for your weight than it was on the MTB.
I don't think truing the wheel is going to make the tire fit. I think it's probably just too big for the frame. People around here like their big soft tires and so we sometimes talk about how much clearance is really needed... although opinions differ, "almost none" is not a favorite answer.
You could probably overfill a GP4000sii 25 or some other true-to-size 28 with no trouble. It will just be a tiny bit harsher.
__________________
Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."
Last edited by Darth Lefty; 05-18-17 at 02:49 PM.