'83 K20 Tire Pressure Recommendation

[MARKDTN]

I have an '83 K20 with stock wheels. I am looking for the recommended tire pressure. I thought it would be easy to find, but it's not. I do not have a door sticker and from what I can see it would be for the original 215/85/16s anyway. I am running 245/75/16 Bridgestone Revo ATs. I have had this truck since '91 and have always run this tire combo, but as I get older I am getting more cautious about tire pressure. I have not really driven it in about a year, and this morning they were all around 40 psi. In the past, I have been putting them around 60 psi, but looking for some validation. Anybody have any thoughts on this?