Offset; how far the mounting point of the wheel is from the center line of the rim. Stock 17" wheel offset of tC is +45mm from the centerline; a +35mm wheel will be 10mm farther out from the car, assuming the same width of the rim as stock (7.0"). A +50mm wheel would sit 5mm farther in, again, assuming same width as stock. Width of the rim affects how far from this imaginary center line the wheel actually sticks out on each side, so an 8" wheel would stick half an inch farther in and farther out than a 7" wheel with identical offset.
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