First, get an accurate pressure gauge that goes TWICE as high as you need - they are most accurate in the middle of their range. A gauge that reads in .1 or .5 psi works well - digital or analog.
Then start with the pressure recommendations in the manual. Tires are all about flotation. Drop the pressure in 2 psi increments and find what works and feels best for you - front and rear. When you get close, use smaller increments.
Different brands and sizes of tire will likely want different pressures. And you may find that in the twisties you want one pressure and on the highway, you want another pressure - on each tire.
I hope this helps.
