Firstly wanna say hi to everyone on the forum..

I've just p/x'd my valver for a Rallye last week, it's not a minter but is a solid car. Basically just needs a few things sorting out to get it perfect. Got a few questions too and thought this would be the best place to ask em..
Firstly, it came with some 17" TSW's on, and they are scraping the arches at the front on tight corners, also the rear ones scrape if i'm cornering on a camber. I wanted to get some new wheels but what are the perect size wheels for a Rallye? I guess 17's are jus a little bit too big?
Also, do I have to buy a Rallye alternator or can any mk2 gti alternator fit ok? Think mine's on the way out as it doesn't charge battery enough and has struggled to start the past 2 days although up until then it has started fine, I only bought it last Thursday, but like I said, i've had no problems with starting till yesterday..
Here's a pic of her:

I know i've got more questions and will add them when they spring to mind, but if anyone could help on the 2 queries i've asked above i'd be really grateful..