For another opinion from
http://www.roadbikerider.com/ua4.htm#The Case for Lower Tire Pressure
DEAR UNCLE AL: Perhaps you can settle an argument at our bike club. I like riding 20-mm-wide tires inflated to 120-130 pounds. I feel faster because of what I think is lower rolling resistance. Others argue for a 23C width at 100-110 psi, saying these tires are more efficient because they absorb pavement irregularities better. I weigh 175 pounds and ride at an average of 18+ mph on a variety of road surfaces. So who's right about width and pressure? -- Greg C.
UNCLE AL FIRES BACK: Soften up, Greg!
Most everyone I know runs too much pressure. Welcome to the club. Over many years of testing and talking to guys who live on their bikes, I'm convinced there is little reason to run more than 95-100 psi -- and there are compelling reasons to run 85-90 psi.
High pressure, say 100-120 psi, guarantees short tire life, poor cornering and lots of punctures. A rock-solid tire cuts/punctures more easily than it would at a lower pressure. Also, a softer tire can "smear" -- conform better to objects encountered on the road. Why make the ride even rougher on America's ever-crumbling road surfaces?
Admittedly, I weigh 210 pounds and ride on really poor road surfaces. These things influence my opinions. I run 85-90 psi front and 90-95 psi rear on 700x23C clincher tires. I do not have flats! Plus, bumps are less of an issue, and my bike corners as if on rails on high-speed descents. I get 1,000-1,500 miles out of a rear tire. When I ran much higher pressure many years ago, I got no more than 500 miles.
So, my advice is never to run smaller than 23C. Use good tubes, air them up before every ride and spend extra for premium tires -- they'll pay you back in extra mileage and better handling.
One more thing: Don't buy a race-specific tire to train on. If it's advertised to last only 500 miles, they aren't lying. Shaving grams off of training tires is silly and wasteful, and you won't get the low-weight advantage when event time comes if you ride the light stuff all the time. Make gram shaving your secret weapon, if only in your mind, when it counts.
Do as I recommend and I promise fewer flats, happier miles and no noticeable increase in rolling resistance (the great myth). Plus, you'll waste fewer resources, both financial and natural.