You should look at the door sticker to see your OEM suggested tire pressure and start there. For my 1500 it says 35 PSI, and I ran that for years on my 265s, 285s and 305s. When I put my 37s on recently I had to go up to 40 pounds to get rid of that "lookin kinda low" sidewall bulge.
If you know how much weight is actually on each axle they make charts that match up tire size and vehicle weight with tire load range and PSI.
toyotires.com/media/3729/application_of_load_inflation_tables_20200723.pdf
Also, if you lift, then lift springs are not the way to go if you want it to ride nice. The more arch a spring has, the worse it rides. The best way would be to use a shackle flip, as it lets you use stock springs for about 4" of lift. You can also go down a spring pack size too. They start at 3/1 for the regular 1500 trucks, 4/1 for the heavy half/light 2500, and up from there all the way to 7/1 I think for the duallys. I went from worn out 3/1 to brand new (not junkyard but actually new new) 4/1s and it's definitely a noticeable difference in ride quality. I almost regret them lol. But I don't, because I have a toolbox, lumber rack and 37" spare to haul around, plus whatever I'm towing or hauling.1
