The new Conti GP Classics are true skinwalls, not gumwalls, and translucent against bright light. I'm assuming that's the base for the entire tire, and the tread is laminated onto that base. But it's 700x25 clinchers only, no tubs. I just got a set, only ridden 'em twice for 15 miles each. They seem good. I'm gonna try 'em again this morning at lower pressure.