Rastus

I cracked a couple of my stock rims a few years ago. The local Mercedes dealership had them welded. I know thats not the best thing to do however I've not had any problems. I moved to a smaller town so welding is no longer an option.
I found out yesterday there's a new crack so I'm going to buy a set of aftermarket rims.
Currently my car has 17x7.5 Front and 17x8.5 Rear. What would be the benefit if I bought a bigger rim, 18" etc. providing it would fit? Is it only aethetics or would there be a performance benefit as well?
Thanks

betrezra

I have a near mint set of 2004 clk 55 rims w new drag radials on the back. Ill let these go very very cheap. Houston texas. Lmk