I'm thinking about going a little wider on my summer tires (I know, early).

235/45 vs. the stock 225/50.

I think that is about the limit of the rim, but is there any reason to not do this. Downside?

 

Technically you aren't really increasing the contact patch, only re-shaping it. On the plus side, you will get more sidewall 'bulge' that may protect the rim better. If you are looking for improved performance, go with the same size tire but a 'summer' only compound.

 

That size is a little shorter than the OE 225's, but it is about the limit width wise for the OE 7.5" wheels.