[Philster]

40 is going to stick out LESS than 38. --- 2 mm less.

The lower the number, the father out they sit.

For wheels of equal width, lower the offset and this pushes the wheel outward. In your OZ 38mm vs OZ 40mm offset consideration, 40 sits farther inward. By 2mm.

 

[Philster]

@tibby -- Roger that. It's just that offset is misunderstood by almost everyone.

I think your thread title might not draw in all the people with assorted wheel and tire sizes that could address rubbing, etc.