Tire pressure adjustment for vehicle load and/or XL tires

[baj]

My '06 2.5i wagon recommends 33 psi front and 32 psi rear tire pressure (tire size is 205/50-17). My understanding is that if a car only gives one set of pressures, it is for light loads (front passengers only, not a lot of luggage) and legal US highway speeds. I once owned a VW which gave 4 sets of tire pressures (every combination of half load, full load, normal speed, and high speed) and these pressures were significantly different from each other -- I remember that in the full load cases the rear tire pressures were much higher (~40 psi). Two questions:

 

1. What tire pressures should be used for a fully loaded car (e.g. family vacation)?

 

2. I have replaced the original tires with new tires in the same size, but the new tires have an XL load range rating. Does the XL rating change the pressure I should be using?

 

Thanks!

[Malt Beverage]

The pressure on the door is typically fine for a "normally" loaded car. Normal being whatever the manufacture states as the max capacity. XL will not make a difference in required air pressure. If your car is loaded like this I would bump up the pressure 2 lbs. Edit, not much harm done by trying to bump up 5 lbs.

 

http://www.swapmeetdave.com/Humor/Workshop/Lumber-Car-A.jpg

[baj]

I don't think the "normally loaded" case is the max weight capacity. Every car I've ever owned that had only one set of pressures listed had the same pressure front and rear or slightly higher pressure in the front. I think if you load a car to max capacity in any reasonable way (people in seats and luggage in the back) there will be more weight on the rear axle. And on my VW the normal load normal speed case had roughly equal front/rear pressures (maybe 32 front, 30 rear?) but the max load normal speed case was more like 32/39 or so.