1969 dodge dart 7 1/4 rearend rim offset and size
Hello 1969moparDART
Check out this clip, It tells how to measure back space in simple terms.
This link explains a little more in depth.
Wheel Offset and Wheel Backspacing
BTW Nice car you have.
Remember measure twice, Order on line once.
Hope this helps.
Happy Mopar :)
Arron