Be aware that if you use spacers you can expect to have to replace wheel bearings
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(particularly at the rear) within a few years.
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That said you could certainly add 20mm without rubbing issues but 25mm might be close.
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I run a 15x7 rear with a 225/50/15
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(so the same as standard) but with a 35 offset rather than the standard 45.
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In other words it sits 10mm further out than stock.
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To that I've added a 15mm H&R hubcentric spacer and the wheel is almost flush with bodywork and indeed used to catch on arches before they were rolled
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(granted though it is lowered an inch and a half).
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Plenty of pictures of
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'flushness' in my garage.
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R.
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