On my 97 mail wagon I sat on the right and when I turn hard left I hear a sound like escaping air coming from the front tire. It is not one solid sound it is like you hear it with each rotaion of the tire. (sis-sis-sis-sis) I hope that is the correct way to type escaping air. It is not the tire or wheel because I put another tire and wheel there and it still does it. Any ideals?

Sounds more like a brake pad rubbing on the disk. Check the brake pads, and maybe clean the dust off the brakes.

 

In general, I wouldn't worry too much about a little noise like that.

While you are checking check to see if the pads are wearing evenly. If they aren't it's a sign of the caliper and pads not moving freely, which will reduce mileage and brake life.