Nothing is written in stone about this topic, but here's my understanding.
- If you want to run any brand 37" tires and want to run the truck hard in the dirt, you definitely need to hammer/trim back the pinch weld.
- If you want to run BFG All-Terrain 37" tires on OEM wheels, you might be able to get away with only trimming the pinch weld.
- If you want to run BFG All-Terrain 37" tires w/ aftermarket wheels (less backspace than OEM), you'll probably have to do some minor trimming on your fenders, flares, and fender liners or get aftermarket fenders/liners.
- If you want to run any other 37" tire than a BFG AT, you'll have to do all of the above with a little more modification to each or get aftermarket fenders/liners.
I think that sums it up pretty good.
EDIT: Netix's truck w/ 39" tires in the photo above is a POS... ball joint spacers... major mods to the firewall... and what not to achieve enough lift to clear those tires. You said you didn't want to screw up your truck to clear 37" tires, so I don't suggest you go the route he did. That's just my opinion.