specialized has armadillo tires, they are super becuase they are almost puncture proof. what kind of bike are you riding? i had spec reso's on my '07 hardrock and they were 2.1's but looked wider. on my current bike, ive got a spec "the captain" 2.3 upfront and a spec "fast track" 2.0 on the rear. i was able to get them on a WTB SX24 rim if that helps. i also run slime tubes so weight doesnt really bother me. rolling resistance is so minimal with this setup, i was able to keep a 14mph cadence through an entire ride :thumbsup: at 45psi (i know, they are full) 