thanks for all the help everyone.

I got in my Continental Contact Cruiser tires today. These things are a good bit heavier than my stock knobby MTB tires (Maxxis Ikon 29x2.2). Old tires spec weight is 640 grams, new tires 1025 grams. I did go for a quick mile through the neighborhood but won't be able to really test them until my regular ride Wednesday morning ride.