Stock size is 15x7..I believe we already mentioned this in the thread a few times. The difference is going to be a inch in width. Therefor you can fit a wider tire on it, but you may run into clearance issues.

I'm pretty sure the center caps come with the rims. I haven't heard of them not before, but double check in the description/fine print. You could alsoo contact the seller to verify.
As for fitting 31's on stock...it's been a debate for a long time. Since you have a 1st gen to the best of my knowledge, yes you can fit 31's without issue. you might see slight rubbing issues with the after market rims though. I'd recommend doing the shackles if you want 31's just to be safe.

 

Thanks for the help i just might try the 31's with shackles

 

my rims didn't come with center caps...

 

Oh really? That sucks. Did you buy them from the same place? That's the first I heard of the centre caps not being included. Grant it I never really looked into it that great.

So cavalier, you'll want to check with the supplier to make sure they are/are not included

 

Mine didn't come with the center cap either.

 

i got mine from 4wheelparts.com I'm pretty sure most places the center caps don't come with the rims.

 

yeah there like and extra 13 bucks a piece but there worth it