Widest tire I've used on a 250 ('72 W114) is a 205/70R14. 225 is pretty wide. What about mounting hardware? You'll need longer wheel bolts just for the alloys, plus an extra 16MM to accommodate the spacers, assuming the wheel bolt pattern/diameter is the same. I'd first want the opportunity to attempt to bolt on one of those rims to test for fit & clearance problems, especially in front.

Happy Motoring, Mark

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DrDKW