Going to the high end on tire pressure maght make your sedan handle like a gokart on smooth roads (or seem like it, anyway) but in the frozen north the wear and tear on suspension parts and wheel bearings comes back to haunt pretty quickly especially with 60 and down series tires. I do a little autocrossing , and I run wide alloy rims with tires to match, Koni struts, and a front strut tower bar and stiffer bushings in the suspesnion links, but I don't see much payback from going over 36 pounds in the tires. . It's all about tire footprint, IS the tire FLAT on the road from tread edge to tread edge? The racer guys use a tread temp gauge to measure across the tread looking for hot spots. Harder to do on the street, you have to resort to looking at wear patterns instead. I have always understood the max tire pressures were for carrying a lot of people and luggage, on a lot summer day, at high speed, not keeping the tires of an unloaded car in contact with a bumpy road. Some IRS layouts introduce quite a bit of camber, overinflate the rear tires and the inside edges wear real fast.