Wheel fitment questions. Width and offset.

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Hello, I'm new here and just had some questions regarding fitting some new wheels on the car.
I would think all the 986's have the same wheelwell dimensions, but just in case, the car in question is a '00 Boxster S.
Using the Hamann front bumper and RUF sideskirts, the stock wheels start looking a bit small, and don't give the car the mean look it deserves.
I would like to put on some 18x9's up front, and 18x11's in the rear. From the little bit of info I can find, others have used 8.5 up front with 45mm offset, and 10.5 in the back with 40mm.
Does anyone know if those same offsets will work with the .5" wider wheels? I'll be using 235/40 up front, and 275/35 out back.

Thanks for any help.