Originally Posted by Andrew010

That would be true with both wheels were the same diameter. Problem is, they're not.

Stock wheels I believe are 8" wide and your 20s are 10" wide.

Offset is based off the center line of the wheel. The center of the wheel is different on different width wheels.

You could compare the 2 on backspace, then do the math to figure out how much wheel is forward of the hub. Then compare those 2 numbers to tell how much further the new wheels will stick out past the stockers.