I was gifted this truck and my plan is to build a wooden tiny house on the back of it. I have got the engine running and started looking for tires. It has 8 22.5s on it right now and they are all dry rot. What are my options to getting some kind of tire that is more available? Thank you for your time,
Kyle

 

Some 235/80 22.5 or 255/80 22.5 should be pretty close in size. Some 11R22.5's would be a fair bit taller and would help if the truck is too low geared for what you are using it for.

 

You lucked out in having the 22.5 tubeless wheels on it. Most had 20 inch widowmakers or lock ring type, tube type wheels. I lucked out recently and found an F350 that I am using as a parts truck and one of its major selling points (besides a rust free cab) was it had six 17.5 tubeless wheels which are hard to find.

 

I'll echo the comments about you being lucky you've got the tubeless 22.5s. But will add words of caution. Your 8-22.5" tires are NLA in this country. They were spec'd for either the 5.25" or 6.00" wide versions of these wheels. The widest version available back then had a 6.75" wide rim, and they are rare in the extreme. The cited 235/80R22.5 is spec'd for either a 6.75" or 7.50" rim. The 255/80R22.5" is spec'd for either a 7.50" or 8.25" wide rim.

The most common tire used on these old narrow rims today is the 9R22.5". It is spec'd for either a 6.00" or 6.75" wide rim. Guys do use them on the 5.25" wide variety, but at risk of having insufficient dual wheel spacing. Use of a spacer between the rear duals remedies this. The tires will crown a bit I'm told when mounted on the 5.25s, but I've heard of no other issues besides the DRW spacing issue. If you can find part numbers stamped on your wheels I can look them up to tell you which you have. Stu

 

I ran 9 x 22.5s on my '56 F500 I had in the 1980s. With the bigger tires it made the 5.83 ratio not too bad. It was still the era of the dreaded double nickel (55 mph) limit still in force so I never hesitated to take it on the interstate. When they lifted it in '87 I had traded the truck for something else.