Wow! Had to doublecheck there and make sure I was really in the 'Commuting' forum!

Personally I like to deal with priorities and if my tires width was actually holding me back, yup - I'd change 'em! But its not.

And if bicycle aerodynamics was holding me back, then since I'm not running 60mm aero rims or a sculpted frame, and in fact have lights and other paraphanalia in the airstream, and a helmet that's probably more of an aerodynamic issue than the tires - its not worth losing sleep over.

And thats without even taking into account that 75% of aerodynamic drag comes from the rider, and I seldom wear spandex while commuting, and often carry a backpack with tools, lunch and a change of clothes, and in spite of all that - its still speed limits and traffic that hold me back. Naaaawww .... personally think I'll stick with the fat tires. The braking performance, long life and comfort I get to use every day.

Just swapped out the Nokian studded winter tires for a summer wheelset. Have 700 x 23c, 700 x32c 700 x 40c and Schwalbe 700 x 50c tires hanging up to choose from. The Schwalbes went on. I can break 55km/h with those in the flats so don't think the width is a handicap - it fact it lets me maintain a higher average speed on some pretty crummy roads.