4x4 fenders

What year 4x4 fenders do i need for a 87 hardbody to lay 18's with a bd to the rockers or is it possible to lay 20's and if so how much do i have to tub the firewall

86.5 to 97 the fenders are the same,and yes to lay 20s you have to tub the firewall, but i dont know exactly how much (also depends on your tire size)