Looking for wheel help for my ranger

I'm looking at a set of wheels and I need to know if the following offsets would work. My truck is lowered about 4" all the way around so I can't have them sticking out past the fender. They are 20x10 with a 50mm offset and I can get the 18x9 in either a 24mm or 35mm offset.  I've seen guys say they have no problems running 18x9s with a 24mm offset so I think I'll go that route.  Here's what I'm thinking, you guys tell me if it sounds right.  If I can get away with a 24mm offset on a 9" wide wheel would it be reasonable to say I can get away with a 50mm offset on a 10" wide wheel since it's 1" wider and 1" = 25.4mm.  Take the 24mm from the 9" wheel and add the extra inch from the 10" wheel (25.4mm) and it comes out to be 49.4mm.  So a 50mm on a 10" wide wheel should work?

Assuming that your running the stock axle in the back and not the 8.8 or 9" I do not see any problems with the 20x10 for the rear. however if it is too close for comfort just go to your local JY and pick up a passenger side axle shaft and cut your drv side down teh diffrence and put the newly aquierd axle in there should give you about 3" total so an inch and a half on each side more clearence many others and myself have done this with our bagged rangers its very easy to do if you can weld or take it in to a axle shop and htey can do it for you too