24.5 and 22.5 wheel- Tires options

Hello team,
I’m doing some ground work for a toterhome build( based off a Pete 387). I had three questions(wheels, tires and gear ratio).
#1 Peterbilt 387 – what is the lowest gear ratio for these models? Need more h/w speed.
#2 24.5 wheels: what is the largest tire that will fit these wheels?
#3 Most of all dump trucks have these wide tires in front. Are there any options for similar setup with 24.5 wheels? If 22.5 is the only option, are there any tires that will stand as tall as 24.5 in #2 above?

 

Thanks, regarding #3-heavy part, based on what the builder is calculating, he says, 12K will be close but might just work. But the important thing is, this will be used off the highway for a fair bit in loose gravel roads etc...need wider tires for sure.
Also, who makes 12- 24.5 tires, I cannot find much online.

 

I must be missing something, I find 12R 24 but no pictures/details on 12 R 24.5.

 

ok, I see it now....thanks again!

 

Sorry, another silly question about 445/65 22.5 I see three variants on this site:

http://www.deltaworldtire.com/445-65R22-5-michelin-products.htm

If I use online tire size conversation tool, the diameter of 445/65 22.5 is 44.8 Inches. Site: http://tire-size-conversion.com/

but the delta site lists height as
[h=1]XFE™ Wide Base Tire as 45.6 inch [/h][h=1]XZL™ Wide Base Tire as 46 inch[/h][h=1]XZY® 3 Wide Base Tire as 45.8 inch.[/h]
Why the variations? I thought 445/65 22.5 would be standard height because of the formula they use to calculate height.