rule of thumb I've heard is typically 1.4x rim width for section width...

6"=152.4mm 152.4*1.4=213.36mm, I I would consider stretching out to a 225, but not much wider....

7"=177.8mm, 177.8*1.4=248.92mm I would go up to a 255 on a 7", but I have heard of people stretching a 275/60 on them

BTW all M body moparts newer than about 82 or so are 7" wide rims, if you're looking for a cheap source of wider wheels.

1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)