50 psi is only for when you are carrying weight or towing at or near the maximum capacity for your truck. Normal psi should be much lower, normally around 30-35psi.
I've got a ranger, so there's very little weight over the back tires. With a tire 12.8 inches wide, it's not a problem. Actually now that I think about it I think I'm at 32psi in front, 25 in rear.
You are correct, a locker is engaged all the time to at least one wheel.
Here's how it works. Lets say you are going straight, the drivetrain is engaging both wheels. Now you turn left. Wheels in a turn must travel at different speeds due to different turing radius's. in an open differential when one wheel goes faster the other wheel must go slower. The drivetrain ends up powering the outer wheel since it's going faster, this helps turning since it's pushing you through the turn from the outside edge. If one wheel is on ice and spins though , no force is left for the other tire on the dry road, so you're stuck. So you're going straight in a parking lot at 15 mph on cruise control with an open differential. you turn. The outside wheel wants to go faster, the inside wheel wants to go slower. you end up with the outside wheel going at 16mph and the inside wheel going at 14 mph. Since you're powering the outside wheel, it assists in the turn, and it's easy to turn the steering wheel.
With a locker of any brand, the differential is set up to have both axles turn all the time. At the same time, it's set up to allow any wheel to go faster than the current rate of speed. Think of it as a large socket wrench. The rachet is designed to push in one direction and rachet back to push in the same direction again. That nut you're turning is actually able to turn faster than the rachet is turning, right? That's what a rear locker does. It forces both wheels to turn at least at the speed the gear is turning, but allows either wheel to turn faster than the gear at any point.
So you're going straight at 15 mph in a parking lot on cruise with a locker rear diff. You turn. The gear is going at 15mph, so no wheel can go slower than 15mph. Inside wheel is going to want to go slower than the outside wheel, but it's being powered at 15mph. That outside wheel is going to have to go at 17 mph, effectively freewheeling faster than the differential. The vehicle is being pushed from the inside wheel, not the outside wheel, so it takes a slightly higher effort to make the same turn. This is called understeer - the car will feel like it wants to resist the turn slightly. No big deal, just something you might notice.
Here's when it can get interesting. Let's say you have a lot of body roll, and the inside wheel, which is being powered slips. the truck slows down slightly, until that outside wheel speed drops to 15 mph. Then with a sudden thud, the outside wheel is the one being powered. you'll get a shift from understeer to regular steering. you inevitably slow down, the inside wheel catches, and you shift back to an understeer condition again.
This sounds horrible but it's not. The less aggressive you are with the gas pedal the less likely it is to happen and the less noticable it would be if it did happen. Just a slight change in driving habits makes it just fine. As I said, my wife never noticed it at all, even in bad weather, until i said something to her. It's all about driving style.
Hope this all helps!
--Bob
