Thank you everyone for your replies. That's a lot to chew on. Just a few notes.
Not sure I can go to a 14". I'm sure I can't fit a 15". I'll have to do some measurements and see. 14" would give me more tire options, but then I need 5, and rims.
From the Tire Rack website, it says industry standard dictates that ST designated tires are rated to 65 MPH. I guess if there is no special speed rating, that's what you go with.
Keeping up with traffic. I'm not talking about doing 85 MPH in Montana. On a 2 lane highway doing 60 MPH while everyone else is doing 75 is not the safest travel situation. I'd rather be closer to their speed if possible.
Let's assume I can't change from a 13" wheel. What are my best tire options?