xS = 225/50/18 all around with 18x7.5 rims

My options for tires are 235/50 or 245/45

 

Ok, but where did you come up with 1" difference in diameter?

Going from a 225/50 to a 235/50 is only .4" or about 1.5% difference and I agree with going with that size as opposed to the 245/45 (which would be all rolly-polly and muffin-top looking on those narrow rims, even though they are only .2" different that the originals).

 

vq, that is correct. For some reason I was thinking the 5mm difference equated to .5 inch

So I have no experience changing up tire sizes but what should I expect moving up to the 235/50? I'd imagine a bit smoother ride, more stable, bit better mpg but little slower acceleration. 225/50 look better too!

I did some searching but its mostly uninformative responses that have no unbias opinions. Thanks for the advice, very helpful.

 

To be quite honest, I doubt you'll notice much, if any difference. There is more potential variation in the performance of different brands/models of tires of the same size than there is in the variation you'd be able to discern just changing the size from a 225/50 to a 235/50 of the exact same brand & model. If you drove two identical cars back-to-back in a blind test, you probably would have a hard time telling which was which unless you were driving REALLY hard. I wouldn't over think it too much, you're gonna be fine with the 235's.