If you want a nice ride, go by the bike's figure. If you'd rather have maximum response to rider inputs and better tire life, go by what is on the sidewall. And buy a kidney belt...the stock shocks with a 40 psi rear tire will bounce you out of the seat if you run over a cigarette butt...
-WD

There's plenty of debate about what constitutes "correct" tire pressure, but I suggest going by what your vehicle manufacturer recommends, which should be listed on the top of the belt guard, or in the owner's manual. Don't confuse the "maximum tire pressure" listed on the sidewall of the tire with the "recommended tire pressure" provided by the manufacturer of the motorcycle. "Recommended tire pressure" is what you want in your tires. If you're carrying an extra heavy load, follow the recommendation for "heavy loads," which is usually listed with the "recommended" tire pressure.

Ready for some  high school physics? Remember that tire pressure will increase as the outside air temperature rises. In fact, tire pressure will go up approximately one pound for every 10 degrees Fahrenheit. So, tires that were at 32 PSI back in January when you stored your bike could easily be closing in on 42 pounds on a hot July day. Under some conditions, that increase in pressure is enough to blow the tire! If nothing else, a tire that's overinflated will wear prematurely and will cause the bike to handle and brake poorly. By the way, while you're out there changing the air in those tires, toss that stupid pencil-style pressure gauge in the dumpster where it belongs and get an accurate, dial-type gauge.

You also have to remember friction. As you ride, there's friction between the tires and the road. Friction means heat--and heat means an increase in tire pressure. So, here's what to do about your Savage's tire pressure: Check the tire pressure before you start riding. If the recommended pressure is 28 PSI, for example, it means 28 PSI before you start riding. If you check the tire pressure when you stop to get gas two hours later, it will be much higher than 28 PSI. If you check it at this point--after you've been riding---there is no way to know what the correct tire pressure should be. You'll be tempted to let air out of the tires, because the tire pressure will be greater than 28 PSI. Do not do this, because the tires will be under inflated.

To make the confusion complete here's what I read in an Old Racing Bikes forum.

Start with the recommended pressure from the manufacturer ( Bike or Tyre).  OAT around 20 degrC.

Heat up the tyre by normal riding your bike.
Check the pressure . This should be increased  around 3 psi .
If the increase in pressure is more (than 3psi) you started with a too low pressure.
If the increase in pressure is less( than 3 psi) you started with a too high pressure.

Make sence?

Greetz
Kropatchek