Tires pressure.

OldGuy

When I brought my car home from delivery, I checked the pressure and it was 40 PSI and I attributed it to idiots at the dealership not knowing what they were doing when they prepped the car. I immediately had the pressure adjusted to the numbers on the jam and have kept it that way since simply because I assume the Nissan people know best. But now I'm going to say the dealership set those pressures at 40 not out of incompetence but for a reason. I like to give people the benefit of the doubt.

Modshack

Cause they couldn't read the door Jamb sticker?

Seriously, most car and tire combination's have a sweet spot they work best at. Different tires than engineered and spec'd on the car may have softer or stiffer sidewalls that may require a change in the pressures. IMO the factory recommendation with these tires are pretty spot on. Raising them to 40 will result in a reduced contact patch, sketchier braking and traction, and odd tire wear patterns.

The Tyre Bible is always a good read if you haven't done so:
Car Bibles : The Wheel and Tyre Bible Page 1 of 4

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