Fitting them will be the only way then really. Iirc std rim is 6j, so your adding 38mm (ish) of width, taking that into account if my memory is correct the inner edge of your new rims will still be roughly 15mm closer to the suspension components ect.

Some manufacturers measure across the rim, some between the beads, so you may have a difference there too.

Dave


(std's are 5.5j, so it gets worse......)