You are probably in need of ball joints and alignment. You really need to have the front end checked by a mechanic for safety sake.
Tires are out of balance
On my 2005 Ford Explorer I have Goodyear Assurance Triple-Tred tires. They are very expensive at $820 with installation, road hazzard warrenty and lifetime rotate and ballence. However these tires are very well suited for the Ford Explorer. Here is a link for convience: http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Assurance+TripleTred
My first Ford Explorer , a 1993 XLT model , came with Firestone ATX all terrain radial tires ( P235 / 75 / R15 )
you can on a 2002
Yes.
On a 1996 Ford Explorer : Yes , assuming it's not the Eddie Bauer version with the 16 inch wheels ( my 1995 Ford Explorer " XLT model " , 4x4 , has always had P235/75/R15 all terrain tires on it right from the factory )
Yes
Depends. All tires have a size on them, so the questions of the year of vehicle is irrelevant. If the size of the 1997 Explorer is the same size of the 1982 Chevy Van, then they are both interchangeable. The problems if any will be in the rims. But if the rims are different then the tires would be different too.
235/75/15
5 per wheel
No , not with out raising the vehicle
My ( 1995 ) Ford Explorer XLT came with ( and still has that size ) ( P235 / 75 / R15 all terrain tires )