For just about every car, there's at least two different "maximum tire pressure" ratings.
- The vehicle manufacturer's rating. This is usually found on a sticker attached to the driver's door.
- The tire manufacturer's rating. This is usually found on the side-wall of each tire.
Given this, I've actually got two questions here. I'm fairly certain I know the answer to the first, but would rather the answerers here respond to confirm. The second is really the meat of things, though.
Which rating should be followed when filling one's tires? Should you use the vehicle's rating, the tire's rating, the lesser/greater of the two, or somewhere in between?
What variables can affect the maximum pressure rating that should be used for the tires? Could some major vehicle modifications, such as drivetrain or suspension changes, make the true "best" fill level deviate from one or both of the manufacturers' ratings?
EDIT: For specificity's sake, I added the safety tag. I'd like this issue more addressed from a safety/vehicle health standpoint, than a racing/performance perspective.