[Z-linkCobra]

I find the best pressure to run is the one that will give you full contact as someone said in an earlier post. Grab you a can of white spray paint. Take your car out to a place that you can run in a straight line or really close to it for as long as possible. use the spray paint and put a line across the tire. Let the paint dray and drive normal for a mile or so. Check your wear pattern and increase or decrease tire pressure until you have even paint removal across the entire tread pattern.

Paint gone on the outside and not the center= under inflated.
paint gone in the middle and not the outside= over inflated.

Chalk works to but can sometimes rub off pretty easy and lie to you. This trick works for your daily drivers as well.