...just a real quick 7.25 mile ride to the public park and back, since I had the afternoon off. I was testing out air pressures in the Kenda K35 27" x 1 1/4 tires that I put on about three weeks ago. Instead of always running 80 psi in the front and rear, I left the front at 80 and pumped the rear up to the max 90 psi. It didn't blow off the rim or have any issues. I honestly didn't feel any difference, other than a very slight increase in overall speed.
7.25 miles in 25:50 for an average of 16.8 mph. (probably where the .8 came from, with the rear at 90psi instead of 80psi).