The OP's connection time in Denver is sufficient and the trains during that period runs every 3-5 minutes...

As another FTer posted, my experience is that most of the larger planes (B767/B777) do board around at gates near the center of the terminal right above the tram stations, so connecting should be no problem (unless there is a delay on the first leg.

I've connected between terminal C to terminal A with 20 minutes, but don't stop anywhere along the way.