Do the Tires on a 2001 Pathfinder match up or will they fit on a 2002 Ford Expedition. ?

Depends on a few things really, the major thing being are both sets of rims the same size, (14,15,16..). If that matches up then basically just do a simple google listing on what size limits your expedition can handle. But for the most part the first listing on the numbers on the size identification (205,215,225..) are you main concern, that's overall width of tire which could rub on your struts or somewhere when turning if they are too big