Both play a major part in clearance, for instance a flat face design, a +20 will fit but +48 might not, conversely you have +10 Deep concave wheel, the spoke design/pitch will still foul the brakes. Basically a wheel design that pushes out from the Hub/Mounting pad will have a better chance of fitting over a big brake kit than one that doesn't.
for example.... Stock VE SSV wheel
Notice the spoke sits flush with the mount, doesn't extrude out. Also the spokes are quite "fat"
VE E1 GTS Wheel
See how the spoke design pushes outwards/away from the mounting pad, despite it's weak as piss front offset, the spoke is also thinner. This is how you get the brake clearance.