I couldn't find a thread that addressed this - might've been too impatient to go too far back. My tire says proper PSI is 40-65 lbs. So - is that 40 lbs?, 50 lbs, 65 lbs? How do I determine? I pumped it up to 55 coz I wasn't sure what the wide range was for. Anyone got any ideas? Its a Trek Navigator 200 commuter bike with Bontrager (sp) commuter tires. I use it on roads and bike trails - paved. The tubes are thorn resistent with Slime. (New Mexico is Famous for Goathead thorns!)