I recently bought a 1989 Ranger and the tires that were on the truck had a max capacity of 50psi, and online it said that the stock tires should be filled to 35psi. Ive always been told to simply fill the tire to the max, but I was thinking that was causing problems when I couldn't get any traction at all the one time it rained. I currently can't afford to buy new tires. Would lowering the psi of at least my rear tires help?

 

Welcome to the forum

Yes, lower the pressure, you will get better traction as more tire surface is in contact with the road
32psi is common

 

That's only if you're hauling the max payload of the tire, which is almost always higher than the max payload of the truck.

 

+1 for each

Agreeing with both Ron and Super, start at 30-35 when not hauling/towing anything. Your rig will have a good ride feel, good contact patch, and wear the tires pretty evenly from the center to the shoulders.

Adjust for loads as you see as necessary.

I run at 40 PSI to help a little with gas mileage and kinda keep the wear even.