SS: That question is about as easy to answer as "What's the best oil?" Tire pressure depends on SO MANY things: type of bike, type of tire (radial vs bias-ply, tube vs tubeless), weight of bike, weight of bike+rider+passenger+luggage, type of riding, overall average speed, anticipated top speed, air and/or road temperature, and even how you personally want to balance tire grip with tire longevity. From my experience, there are some general "rules of thumb": 1) You really can't go too badly wrong sticking with the manufacturer's recommendation in the owners manual. (This assumes you haven't dramatically changed the type of tire that came on the bike as OEM.) 2) Generally, the heavier the bike and it's load (rider+pass+luggage) the higher the pressure. 3) Lower pressure will usually result in a shorter tire life. 4) For extended extreme speeds (i.e., >120-130 MPH) you should bump the recommended pressures up several pounds. NOTE: THIS DOES NOT EQUATE TO BETTER HANDLING!! 5) For track days, most run lower pressures than typical street pressure for increased grip. 6) For colder air/pavement temps, slightly lower pressures give better grip. All of this shouldn't be taken as gospel, but is a short summary of what I've experienced over about 50 years of riding both street and dirt. Never exceed the maximum pressure listed on the tire sidewall, and don't exceed the GVWR of your motorcycle. When I say 'lower' or higher' I'm generally talking just a few pounds of inflation. For instance, I typically keep my tires inflated to about 34/36 F/R (Suzuki DL650, ~525#, DS radial tires) for normal commuting. If I plan on running the backwoods aggressively, I lower the pressure to 32/34. In winter weather, this might be as low 30/32. When I load up for a trip, whether it's on backroads or expressway, I air up to 36/38+. And I never have any tire problems on the Strom with extreme 130+MPH speeds.... BTW, I ride the poor little thing pretty hard and typically only get 5000-7000 miles out of a set of tires. My front usually lasts a little longer than the rear, but I pitch it when it gets triangulated, even if it still has some tread left.