If you got your M3 new, your car did not come with runflats (did you buy used?) I wouldn't switch to those front tires even if free, 235/35 is quite a bit shorter than stock and you will lose grip from arguably an already under-tired front. 245/35 is perfect for an 8.5" wheel, that is what comes from the factory if you get the stock 19s. ZCP wheels are 9" wide in the front and work best with a 255/35 front. If you can get just the rears from the C63, get those and pair with RE11s in 255/35 for the front, that would be a great setup on ZCP wheels. Check the load rating for the rears though.
16 GT3 | DBM