>> >Under no circumstances exceed max on sidewall.

I agree with this, 8 psi over is 20% which would generally be significant in 
an engineering calculation.

The key to this is to buy tires with a 50 psi pressure rating.  If you have 
gotten lower pressure tires you should not over inflate them.  50 psi tires 
can be hard to come by.  We have run both on our van and the high pressure 
tires definitely ride and corner better.  

I have Michelin XZX on right now.  The dealer erred in the order and got low 
pressure first; he was a good dealer and let me take a vacation (6000 mi. 
and I told him ahead of time) on the tires and then replaced them with the 
high pressure tires when they came in.  Because of the good way I was 
treated he has a permanent customer and I recommend him to others.  Dealers 
will tell you that high pressure tires are no longer made (they are), that 
it doesn't matter (it does), And they can err and order (or their warehouse 
can err and ship) the wrong tire, read that side wall before they are on the 
rim.

My door post says 39 front, 48 rear
I inflate to 35+ front, 45+ rear unless heavily loaded.   

Charles Vaughan
'84 GL