Took the bike to I Martin Imports to have the tires and tubes changed. I really wanted to get slicks on the bike to help me with a little speed. Also, the other tires were original to the bike as were the tubes, and both were now four years old. The tires were not showing any cracks but the nubs were quite worn down - and there's a big difference between bald tires and slicks! (I will keep the old ones as a backup because you just never know, or I may donate them to the Bicycle Kitchen.) The slicks had actually been transferred from one of the Helen's Cycles stores to I Martin Imports for me since I Martin didn't have them in stock. I just left it in their capable hands to do what needed to be done, and they did it.
When I picked up the bike at the end of the day, I noticed that the tires seemed slightly bigger. Not that they don't fit the bike, just they seemed bigger. Turns out they are Bontrager H2 plus, which I think is the hardcase tires, and their tread is exactly like this (image taken from Google):