I think that the ET28 means that the distance to the plate where the bolt holes on the rims are is less...so by adding spacers you push them out to a point where they dont hit the inner arch wall....i got fed up with looking for Fiat alloys (everyone saying i needed thin width expensive tyres and wobble bolts) for my mk1 and jus stuck a set of Bravo HGT ones i picked up off ebay cheaply....fit fine with 50 width tyres....watch the width on them aswell...if your not wantin 2 cut your arches 7" mite push it a bit...but nothing major =)