They are Soma New Xpress KV. Funny, I hadn't even heard of the C-Line tires, but I just looked them up and they are nearly identical. Soma's website states the difference is that the New Xpress tires have Soma's "HyperTex Casing" which they describe as:

"Tough like Kevlar, but more supple so it won't ride like a brick. Cut resistant and pinch flat resistant."

So HEY, I learned something new today! Beautiful tires and while we've not had a lot of time with them yet, they've been awesome thus far. Also, love the username!