I have a 1999 Forester S with almost new tires (215/60R-16) that isn't currently running and a 2003 Legacy L SE.  Is it possible to put the Forester  wheels/tires on the Legacy?

 

The wheels will bolt up.

 

The tires are a bit bigger, the stock Legacy size is 205/55r16, which calculates to 24.8" tall. 215/60r16 calculates to 26.2" tall. Also 10mm wider. They would probably work, but they might rub when loaded, or turning sharp. 

Put your hand on top of the tire and move it in until it is directly under the upper ball joint.  If the top of your finger touches the ball joint while resting on the tire, then no, you can't use them.  It would help if you can lift your finger at least a 1/2" off the tire before hitting the bottom of the ball joint.