28’s will be fine, better yet if you run them low pressure. Even in the rain, most of the trail is hard packed and drains well. Like others mentioned, the section between Frostburg & Cumberland is a little more loose/rough but not a huge problem. Suggestion: Start somewhere like McKeesport where parking is free. Assuming you’re taking the Cumberland to Pittsburgh train, it doesn’t arrive in Pitts until near midnight. Get a nearby hotel (Drury is nice) and ride to your car the next morning. Saturday mornings are nice as there's less traffic downtown.