ok. so i'm thinkin i MIGHT have my head around all this offset stuff.

right now i have OEM rays. so the rear would be like this...

factory:
8.5 in
+33 offset

with 25mm spacer:
8.5 in
-the 25mm spacer = +8 offset as my CURRENT OFFSET.

now if i got a 9.5 rear to have a similar fit as i do now...
9.5
+8 being my current offset + half of 1" being 12mm = +20

and if i wanted to get a 10.5 rear with similar fit...
10.5
+8 current offset + 1in/25mm (half of the 2" wheel width gain) = +33

is that right?

i'm trying to figure all this stuff out thru my own homework...and i THINK this makes sense in my brain. but then i start thinking about lip size and stuff after going to a wider rim, then wonder if the offset changes it's "zero position" when it's wider, like if i go 2 inches wider does that put an inch on each side or all to the outside?...............now i'm confusing myself again.

your help is appreciated. thanks!

 

Almost, you had the stock wheel + spacer correct but a 9.5 or 10.5 wheel may have a different offset so adding a spacer to that offset will give you the correct number. Example 20x10.5 + 33 subtract your 25mm spacer leaves you + 8 offset. Another example 19x9.5 + 17 subtract your 25mm spacer leave you. with -8 offset.

 

but i was basing that off of my CURRENT offset. like on my 10.5 example, the +33 i came up with would put me at the same fitment as my CURRENT fitment, WITHOUT spacer.

sorry guess i didn't make that clear, those later numbers are what i would want to fit similar to my CURRENT setup, but WITHOUT spacers.

 

Make it easier on yourself.

http://www.1010tires.com/wheeloffsetcalculator.asp

Zero offset is dead center of the rim. The numbers that you are getting ( +8, +19 etc) is the amount that the mounting surface is "offset" from the center of the wheel. So you are correct in your thought. If you have a 8" wide wheel thats +0, making that wheel a 10" with the same offset would add 1" to each side of the mouting surface.

 

here's a qucik overview on how to figure out offset on a wheel. good to know if you've ever bought used wheels where the stickers were removed or barrels have been changed out.

How to measure offset

 

I love these vienna Kries, wish they'd bring them back. Saw these on Superstreet recently. He had them painted though