Yep that's correct. The lower you stand the narrower of a tire you'll have to run. Get your truck off the ground, pull a wheel and start measuring. That's about the best way to go about figuring it out. What fits 1 truck might not fit another truck due to the suspension, wheel offset, the difference in deflection on different 4 link setups. Someone might be able to give you a ball park number ,but if you really want to squeeze every little bit of room out of your fender and frame clearance just figure out exactly what your truck has and stuff it full of rubber lol.