Ok checked with the "bike geek" squad. Skinny on tire pressure: Check the pressure recommend on the tire itself. Use the appropiate tubes (not all tubes are meant to be blown up to 140 psi). It is not necessary to let the air out between rides but it is important to check air pressure before a ride. A properly inflated tire means less risk of puncture and offers a smoother ride.

Mountain bike tires (wide, knobby tires between 1.9 - 2.4 " wide) generally take much less pressure. If using the bike on road or trail it can be inflated to around 40 - 45 psi but no more. On trail, singletrack etc. and depending on surface materials (ie sand, loose dirt, hard packed) use run at 25 - 35 psi. Where I ride there is alot of sand so I run my tires at approximately 30 psi. Less pressure gives you more trail "grip" but something you lose alittle control. Higher pressure gives you ability to ride faster but can be "squirrelly".

As to road bikes depends on the tire and tire size. Very high quality racing tires, at 21 - 23 cm can be run up to 140psi. normal tire pressure is 100 - 120. I used Gatorskin 25's on my road bike. I inflate them to 100 psi. They can go to 120 but I like the smoother feel of lighter pressure. Some tires, especially if they are 25's or 28's can run at 85 - 90psi. Basically the bigger the tire the lower the pressure.

Just alway remember to get a couple of things before a ride. 1) tire pressure, 2) condition of drive train and 3) proper adjustment of wheels, brakes etc.

I thank you "bike geeks" !