235/60/15 on front of duster?

actually, in my experience a 7" wheel is 8'' outside to outside and for a zero offset, should have an 8" bs. All my wheels follow this rule.
All my alloy wheels are even stamped that way; ie, a 10incher is 11" outside to outside..

BTW
Notta chance would I run a 275 on a 7" wheel; which is even smaller than the checking wheel. Sure you can install them on 7s; but at typical pressures the centers will be burned off in no-time.
A 275 should go on a 9.2" wheel which rounds up to a 10, or down to not less than an 8.5.
to get decent treadlife, on the street, here's what I have successfully run ;
275/60-15s on 8.5s at 28psi, and
275/50-15s on 10s, at 26psi, and
295/50-15s on 10s, at 24psi, No more!
Your results may vary.