Rim Offset - How to measure it and get it right

[GeeCee]

Firstly this is a Nissan Patrol Forum so note that the standard offset on a Nissan Patrol is +10 or positive 10.

Only if we are talking 8" rims.
The offset for 6" rims is +30, so when talking offset, it is important to also note the width that it relates to.
What the difference in offset does for the different rim widths, basically makes the backspace the same (approximately 123mm vs 120mm).

Very confusing when people talk of Toyota offset and Nissan offset.

on an 8 inch rim i think they are 200mm wide (you should measure to make sure as every rim is different). zero offset would measure 100mm. Negative 22 offset (considered Toyota offset by most) would measure 78mm to the back plate. Standard Nissan offset of +10 would measure 110mm to the back plate.

Not quite.
The rim width is the internal distance between the beads. The nissan 16x8 steel GU rim is 203mm between the beads, and approximately 230 from outside flange to outside flange overall, which is the measurement you need.
Using these numbers (230mm),
zero offset is a backspace of 115mm
-22 offset is a backspace of 93mm
+10 offset is a backspace of 125mm

When I measured up some GU 16x8 steel rims, I had a backspace of 123mm which calculated the offset as +8.

When looking at alloy rims, while the rim width will be the same between the beads(for the same rim width obviously), the flange width tends to be thicker than steel rims, so for the same offset, the measured backspace is larger, or to keep the backspace the same, you have a lower offset.