BRYAN C. - I don't have any experience with Carlisle Tru-Power 26-12.00's, but my 26-12.00 Firestones seem to make the back of my 982 sit just a bit lower than the old Carlisles (Not Tru-Powers) did.
I'd really like to put a set of V61's on the frt of my 70 & 72, the factory tires on both are getting very weather checked, and the casing, cord plys rip/fail occasionally, but they don't make a 4.00/4.80 X 8.
ANYHOW, the narrower 8-1/2" wide rim will round out the tire profile more than the 10-1/2" wide rim, but watching inflation pressure, running a couple pounds less PSI will make them put the full width of the tire on the ground. The over-all dia. of the tire shouldn't vary much with either rim, maybe 1/4" of dia. at most, the narrow rim just sucks the sidewalls in more. If the V61 18-8.50's are taller than your current frt tires your 1572 will have a nose-up attitude, but probably not that much.
Far as plowing with those 26-12.00X12's, you won't be able to tell ANY difference between 8-1/2 and 10-1/2 in wide rims. The 12" wide tire will compact a bit of the last furrow turned but won't effect your traction on the furrow wheel. I've plowed with my 982 a bit following 10" Brinly plows and the land wheel ALWAYS spins first. Even with full size tractors you struggle fr grip on the land wheel first. We ran 15.5 rear tires over thousands of acres plowing with 14" bottoms without issues on the furrow wheels, I've even used 18.4's in 14 inch furrows!