Everyone in the Prius community who reads this newsgroup or any of the mailing lists and web forums knows about increasing your tire pressure to increase mileage. Hell, I'd heard about and been doing that for years on my previous cars, too, just not to as high a degree as now.
Yesterday I had a flat tire, took it to a tire store to be repaired (ended up needing it replaced, but that's another story). The manager I dealt with asked if I was aware that my other tires were at 40+ psi, and I told him yes, that it was intentional for better mileage. He understood and even explained how it works to another customer who was standing nearby, after telling the mechanic to reinflate the tires as I had them.
Well, the mechanic came out front a minute later and "explained" that the tires are only rated for 35 psi and that overinflating them would cause the sidewalls to give out. I said okay and drove off, then of course inflated them to 42 front/40 rear on my own as I'm accustomed to doing anyway since the Toyota dealership never gets it right. It just gets me that this guy would say something like this when, right on the tires, in raised lettering, it says the maximum pressure is 44 psi.