navigator wrote:interesting debate, If you think about it like this, the length of the tread never changes.
I think we can test this.
I think if you aired down one rear tire on one side and put a chalk mark on the tire and pavement and drove one complete revolution, make another mark on pavement and measure the distance.
You could then repeat the process with a full pressure tire and see if there is any difference in the distance.
I would think you would want to at least do the same axle to make sure the weight is similar. You might even be able to do the opposite side at the same time.
Another test might be to do all 4 at one time. Air down tires on 2 different corners. Compare front to back and tires on the same axle. Maybe do 40lbs in one tire and 15lbs in the aired down version.
Or, you could read my post above, and test it by driving a 2002-2005 Impala (or any of the other vehicles that were like this) around after letting some air out of one of the tires, and waiting for the tire pressure monitor system to kick a low tire pressure light, because THE DIFFERENCE IN ROTATIONS PER MILE CHANGES WHEN YOU LET AIR OUT OF A TIRE, AND THAT'S HOW THESE SYSTEMS WORK! If that wasn't the case, I seriously doubt that there would be several years of cars out there that reliably use this system to monitor for low tire pressure. End of thread! Regardless of how or why it happens, it happens, or these systems would not work.
Mike