questions about offset/back spacing

781 Views 3 Replies 2 Participants Last post by  2011 ASSAULT 800
Well I have been thinking about wheels lately, so depending on how my income tax goes as I am expecting alot this year I might get some new 20's to use in the summer. I have been reading alot and trying to understand the backspace and offset thing.

From what I understand the less the backspace is the lower the offset number becomes? and from what I understand my stock 20's have a backspace of 5.5" and an offset of +18mm? So if I go with a backspace of 4.5" which is -12mm on a 20x9" wheel how far are they going to stick out?? I want them to stick out a bit as I am going to add fender flares because my rear fenders are rusting again, so I am going to fix them up nice and good and then hide the back yard fix job with flares, plus add a bit more look to my truck.

Also is there any reason I should look at 20x10" wheels? the price is the same, im sure my tires would like the 20x10's a bit more but will this make it stick out too far?? Any help is much appreciated!

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You're on the right path.
If you take two wheels both 9" wide. The first is your stock wheels +18mm offset(use that as your baseline). and the second is the -12mm offset.
The new wheels will stick out 30mm more than the stock wheels, or roughly 1.25". The increased outer position will result in increased space between the wheel and the suspension. For the 10" wide wheels you will need to factor in 1/2 added wheel width on each side (inner clearance and outer postion)
So if you go to a 10" wide wheel with a -12 offset it will stick out about 42mm more..
+18mm offset (stock wheel) then the change in offset of 30mm put it at -12mm offset. Since you are now running a 10" wide wheel the outer edge will stick out another 1/2 inch Or about 12mm. While losing 1/2 on the inside.
hey man thanks! That is about the number I was thinking for how far they would be sticking out. I think that will be good, the tires stick out a hair being that they are 12.5 on a 9" wheel. Took a little while to understand, but it is fairly simple now that I do. I appreciate the response!
I guess I could have ask originally but if any has an pics of their wheels (perferably 20x9 but will take any size x 9" wide) on their truck feel free to post, that way I get some sort of an idea how they may look! Thanks, Dan
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