You got a bad set - i've had this happen on occasion. The tire is too small diameter. The $1/week Chinaman who made them got the settings on the machine wrong.

this is my durable, cheap, decently liteweight fave:
http://www.nashbar.com/profile.cfm?c...to%2026x1%2E75
1500+ miles with no flats. roll fast, stick well, good ride... better than some name brand $20tires i've had

cheers