There are some companies making a 7R X 15 (the radial replacement for the old 7.00 X 15 bias ply), but most people are using the 225/75 X 15 ST tire. However, lots of people are having troubles with the newer "ST" tires. Yokohama is one that I know makes the 7R X 15 tire in a load range D.
"To compel a man to subsidize with his taxes the propagation of ideas which he disbelieves and abhors is sinful and tyrannical."-- Thomas Jefferson
'08 34' Classic SO, '12 Ram 2500 4X4, 6.7L Cummins.