That sounds fun! Let’s start by reviewing the most important features in off-roading wheels. You need something strong and lightweight. The wheels should also repel debris to provide peak performance on cluttered roads. Grip and puncture-resistance are probably important, oo.
For most people, 17-inch wheels will be the best option. This size wheel will fit nicely over your brakes while still allowing plenty of sidewall.
Here are some tire brands beloved by Subaru owners for off-roading:
You will probably need aftermarket lug nuts. Check the hub bore size on your wheels before you go shopping. Offroaders may also wish to buy front and rear bumper underguards to protect the undercarriage.