[dhgeyer]

Actually, I think a somewhat softer tire does increase traction, as it creates a little bit larger contact patch, and the rubber that is in contact with the road will be more flexible (less rigid). Also, the increased flexing will keep the rubber a little warmer, and warmer tires grip better than colder ones. I agree that lowering the pressure will increase tire wear, so that's a trade off. I also agree that if the tires are too soft, it can adversely affect handling. It's a matter of degree. I would never go as low as 20 psi.

The tire pressures recommended in users' manuals vary widely from bike to bike. The GZ250 manual calls for 25 psi in the front, and 29 psi in the rear. On my Concours, a much heavier bike, the recommended pressures are 36 psi and 41 psi. The max pressure allowed by the tire manufacturer for the tires I have on the Concours is 42 psi.

Some people (including me) run their tires at a bit higher pressure than the bike manufacturer recommends, but never over the max listed on the tire. That's in good weather. This increases tire wear, and I think also gives a little better fuel economy. Some shops, when they service bikes or install new tires set them both at 40 psi regardless of the bike manufacturer's specs. They do this to increase the useful life of the tires.

In situations or conditions where traction may be compromised, I let some air out. I keep them a few psi softer in the Winter.

I check my tires with a digital gauge whenever there's a significant change in the weather, or every few days if the weather doesn't change. As a rule of thumb, every 10 degrees fahrenheit of temperature will increase or decrease tire pressure about 1 psi, although this does vary with tire size and design. Tires should always be checked cold (before riding), and most days it gets warmer later. So, if I'm checking in the morning, and the forecast is for 30 degrees warmer in the afternoon, and if I'm doing a day ride, I set my tires a about three psi lower than what I want for whatever the conditions are.

It's good advice to keep a close eye on tire pressure. I do a pre ride check every riding day before I ride, and if I'm not checking my tires with a gauge, I at least give 'em a good kick to make sure they're not noticeably soft.