I 100% aggree with rotation then changing all 4 tires when it's time to do so. I never changed only two........always the four...much safer way to go. Very interesting all of the responses.

Since Norsky brought up AWD...did ya'll know that as little as 1/4" difference in the circumference of the tires can create a problem with the transfer case? This could be simply from less/more air pressure in one or more of the tires, different wear amounts, different brand tires, or even different tires the same size, from the same manufacturer.
This makes it REALLY important to change all 4 tires on AWD vehicles, not just 1 or two at a time. And...just so you'll know, there is a big difference between AWD, and 4wd...
I'll take a look at the vid now...

Interesting...what a sales pitch, eh?
Like Ken says, there are simply too many variables to definitively say "This is the right way to do it".
Did ya notice they say, "This car has new tires on the front, and tires with 50% tread on the rear"...but....they don't say how old the tries on the rear are, or how hard a compound they are, or are they street tires/mud-snow/all-weather, etc? And you CAN see the guy in the blue car tweeking the steering wheel BEFORE it starts sliding around...
Is is good info? Yeah, prolly, in some instances, but not always. Kay-Sara Sara....Adams' Apple2009-04-20 19:33:04