too many variables to even begin making recommendations.. so i'll just relate an appropriate personal experience and the OP can extrapolate... or not.

at the beginning of a nine month loaded tour, i had 650c wheels with pretty much the standard width tire for that sized rim of 20mm. they didn't at that time come much wider. i didn't know better. i probably ran them at about 100PSI. they wore out in about 800 miles. so i put on another pair when in Phoenix.

after crossing Texas from El paso to the Sabine River and it's chip-seal from hell roads, i'd had enough, so when i got to Gainsville Florida and needed new tires yet again, i took a grest interest in wheels and tires and t found that 26" MTB rims and tires (1 inch in front and 1 1/4" in rear would work. so i built a set in my motel the next day rode for the next 6 months at about 90PSI in front and 75PSI in back. it was much better and the tires lasted for the entire 6 months and then some.

take from it what you will.