dssur
+1y
need to know width. otherwise offset numbers are completely arbitrary.
offset is the amount the wheel mounting surface is "offset" from the wheel centerline. so +38 on a 7 inch wide wheel means you add an inch to the width for the beads, 8, and divide by two to get the wheel centerline, 4, and add 38mm (in inches that is 1.5) and you have a backspace of 5.5 and a frontspace of 2.5. But on a 9 inch wide wheel, add 1, 10, divide by two for the centerline, 5, add 38mm (1.5 inches) and you get a 6.5 inch backspace and a 3.5 inch frontspace. If the +38 7 inch wide wheel barely cleared the fender, the +38 9 inch wheel will stick out an inch, even though they have the same offset.
So post width when asking offset or backspace questions.