[A/S] Tire equivalent size

["David Crook" <blackbamboo@xxxxxxxxxxxxx>]

I am getting ready to buy new tires for our Overlander.  Currently have
750 X 15LT’s bias ply tires, stock original Airstream steel wheels . . .


Questions,

1. Marathons vs   the new Goodyear G614 RST Which is best? Why?

2. What size? 

3. Can I switch to the radial without problem?

4. Load range C? D?

Thanks, David