The tires that came stock on my Tricross Expert were 45's and I rode those for quite some time on my 25 mile commute. I forget their name but they were a Specialized brand tire that was nearly smooth in the middle portion and heavily lugged toward the edges....some cyclocross offering of theirs.

They were definitely slower, but it made the bike feel like I was riding on a cloud. They did make a difference in how long my commute took and took more effort to get/keep speed, but I got there in more comfort so it was a trade off. My big mistake was switching down to 25's and feeling like I was going to have my teeth shook out of my mouth. I ended up trying two other sets of tires before giving up as it just didn't want to give me a smooth enough ride unless I had wider cyclocross tires.

I also rode the same roads with a steel beater road bike and the same tires didn't have nearly the same issues.