i'm getting lost now....275/55/20 is smaller diameter then 275/60/20?...If i'm rite, by how much..?

 

1.1" overall. .55" sidewall difference. ( just over 1/2" shorter sidewall).
https://dodgeforum.com/forum/3rd-gen...ifference.html

 

You can get them here

 

Do a search at Tire Rack for 275/65R20....lots of selection and pretty close in size.

 

what's a rim?

do you mean a 20 inch WHEEL?

 

Going to a smaller diameter tire gives you a mechanical advantage when towing by increasing your effective gear ratio. It's an inexpensive alternative to replacing the stock gears with a 4.10 or 4.56 ring and pinion.

Although not specifically made for towing applications, the Cooper LTZs are a good over-all tire choice. Unlike many function specific tires that excel in some categories and are weak in others, the LTZs have acceptable or better ratings across the entire spectrum.
Another good choice for hauling and towing applications would be the Nitto Dura Grappler, a tire that is specifically made for towing and hauling. It's long wear ratings are phenomenal...