Continental Sport Contacts are another very popular commuter tire around here.
They roll a bit faster then the Marathons, are cheaper and lighter. Puncture protection is still very good, though not on the crazy level of the Marathon Plus with its half-inch of rubber on the thread area.
Recommend my a commuter tire...
Intense Zero's? Not quite a commuter but I'm loving mine. Just had my first random tube failure. Let it sit for too long, it deflated and no longers hold air.
For a nice large pic, click this:
http://photos.nsmb.com/files/2/1/1/7/3/evil2b.JPG
protect tom mcdonald at all costs
Schwalbe marathon duremes could be a good balance: lighter than the marathon plus or XRs, consequently don't have quite the same near-absolute flat protection. (One flat in six months, riding through a construction site seeing if the duremes were as bullet-proof as specialized crosstrails .. nope.)
They aren't light on the wallet though.
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