UPS rang my doorbell today... :)

semtex

You're going in the wrong direction. The larger the offset, the more the wheel sinks into the car away from the outside edge of the fender. Try to visualize this. If you have a wheel with a zero offset, that means the hub is right dead center in the middle of the wheel (if you were looking down at the wheel from the top, vertically). Now let's say you have a +20mm offset. That means the hub is pushed 20mm out towards the outside of the wheel. But what happens when you mount it? The further the center of the wheel is pushed outwards, the more the entire wheel will sit inwards when it's mounted. The offset for the stock 19" rears is +30mm. So if you wanted to push the wheels, say, 10mm out towards edge of the fenders, you would deduct 10mm for a target offset of +20mm.

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