I'd be less concerned about the weight than I would about all that sidewall flex. There's a reason ALL racecars go to pretty much the lowest sidewall allowed by their rules...they perform better.

To say nothing of the tires you'll chunk. The taller the sidewall, generally speaking, the easier they are to chunk. Chunked tires is the absolute proof of false economy. Do yourself a favor, true 'em down to 48.