According to the owner's manual and the driver's door sticker, the 
stock tires should be inflated to 28 psi front and 26 psi rear.  
You can increase the pressure to get a stiffer ride, more 
responsive feel, and slightly increased fuel economy, but do not 
exceed the recommendation stamped into the sidewall of the tire.
Most drivers keep their tires inflated to between 28 - 30 psi, 
providing a good compromise between performance and comfort.  You 
should experiment with tire pressures and go with what works best.  
Note that there are also certain low-traction situations (such as 
driving on sand) where lowering tire pressure can improve handling.

I has been noted by several owners that their vehicles were delivered
with tires inflated to 40-50 psi.  It is reported that Toyota ships 
their vehicles like this to prevent flat spots on the tires in transit.  
Some dealers apparently forget to check this; the result is a very 
harsh ride and a potential for premature tire wear.  All owners should 
check their tires as soon as practical after taking delivery.

Some parts © 2009 Advameg, Inc.