I used to believe that . . . before my old Honda (26 psi) hydroplaned excessively (fixed by a 6-8 lb boost), and before the deadly Ford Explorer-Firestone fiasco, where Ford's too-low tire pressure label was one of many contributing factors. Since then, even my favorite independent car shop portrays tire pressure as a compromise between many competing factors (comfort, handling, comfort, fuel economy, tread life, and did I forget comfort?) and figures 3 lb over the label is a better default pressure for this climate, without even asking customers. My Toytoa dealer delivered my Prius with 40/39 psi, and numerous other posters found similar pressures, apparently what the factory loaded for the boat ride. If there is a problem with this, then Toyota needs to perform another safety recall to catch tires that were not properly prepped before delivery. "Use the Search button" was a very common reply here last year. But for the lazy, here is one of many prior (and contentious) threads: Tire Pressure for a layman. The mentioned articles are linked in my post #13. Because tire pressure is a compromise among conflicting goals, pick a point that best values your particular needs. I drive in the rainy Pacific Northwet, so hydroplaning resistance is essential.
Let's see. Tires have differing max pressures. That would mean that "optimum" is changeable and that car makers choose something they think will work "OK" 99.9 per cent of the time, but it's not about optimum... it's about CYA. Does that make sense, of do we need to talk about tolerances in like 500 other arenas?
