I have 4 guages, and every one reads a different psi with a difference of 8 being the most and 3 the least. 2 are the exact same model, and still read different. These aren't cheapies either! They range from $15 to $50, and I have 4 because I have one in each car. So personally I don't think anyone knows what their tire pressure really is.
Sharkey, here is the simplest description of the 10%/20% method I THINK heathun is referring to. If I'm wrong, I'll accept the flame.
"A technique for those wanting to get the most out of their tires on the street is to use the 10/20% rule.
First check the tire pressure when the tire is cold. Then take a ride on your favorite twisty piece of road. Then, measure the tire pressure immediately after stopping. If the pressure has risen less than 10% on the
front or 20% on the rear, the rider should remove air from the tire. So for example, starting at a front tire pressure of 32.5 psi should bring you up to 36 psi hot. Once you obtain this pressure increase for a given rider, bike, tire, road and road temperature combination, check the tire pressure again while cold and record it for future reference.
Each manufacturer is different. Each tire model is different. A tire design that runs cooler needs to run a lower pressure (2-3 psi front) to get up to optimum temperature. The rear tire runs hotter than the front tire, road and track. So the rear tire cold-to-hot increase is greater. Dropping air pressure has the additional side effect of scrubbing more rubber area.
When I used the tire pressures recommended by Ducati (32.5F/36R) for my 916 on my favorite road, I got exactly 10/20% on a set of Bridgestone BT-012SS. So I guess I’m an average rider and the BT-012SS runs at an average operating temperature compared to other brands.
For the track you’ll have to drop the cold tire pressures an additional 10/20%. Track operation will get tires hotter (increasing the cold-to-hot pressure range) so starting at say 32/30 psi now should bring you up to the
same temperature (and pressure) that 35/39 psi gave you for the street.
Don’t even think about running these low track cold pressures on the street.
Finally, dropping tire pressures on street tires for track use has its limitations, so street compound tires on the track often get too hot and go beyond sticky to greasy. That’s why you have race tires. Race tire compounds are designed for severe operation at these higher temperatures for a limited
number of thermal cycles. On the other hand, race tire on the street usually won’t get up to the appropriate temperature for good performance. At street speeds, the race compound often won’t perform as well as a street tire."
Before your criticize someone, walk a mile in their shoes. That way, when you do criticize them, you're a mile away and have their shoes.