They are 20s, I bought these used from Mike (MCHM3). The rear tires are 285/25/20. The offset of the rear wheels make them a bit wider than the fenders and it rubs a little when I have rear passengers. Those tires are a little too small for my taste, so I bought 2 pilot sports 285/30/20 that I will be installing soon, maybe those will rub a little more with rear passengers.
You're correct. It'll look better with the 285/30's but you will rub. You might even rub without passengers.
What size tire are you running in front and are you rubbing?
The reason I ask is because I'm currently running 245/35/20 in front on 20" Asanti wheels and I rub on the driver's side when I'm on the freeway and go over a deep dip on the road. I noticed it rubs on one of the tabs that holds the front bumper to the fender. Also, I'm on stock ride height. I'm not lowered.