I've had to remove a spare on many of these trucks in the last few years. They tend to rust just like yours. When you tighten the lugs, things feel soft.
I swapped out the spare on my truck for a machange to the aluminum wheels I have.
https://lancaster.craigslist.org/wto...214243264.html
I like these wheels. You could even use an aluminum you have in the spare position.
Your tire sizes are right. I like the Gooodgear Adventure tires with Kevlar in a load range E. I run them and get 50k and they work very well in all conditions.