Factory wheels

I agree with tire manufacturer specs. But, be sure you measure rim width correctly - as 'bead to bead' - not overall physical width, which would measure as one inch wider. I have factory 5.5" Magnums on Challenger and went with 215 by 70 - (14") as they have just about 7.0" of tread. My Swinger, if ever on road, will have 6.0" argents but likely same tires. I like more stock appearances - keeping in mind that OEM tires of the day were significantly narrow - ie: E70 or F70 - 14" (bias). If O.P.'s factory rims less than 5.5" suggest bit wider.