19's are huge...
Look at this thread for ideas on offsets for 11" wheels on 285s and how they'll work with the suspension and fenders.
The 9" width should be fine (depending on offsets) but you'll definitely need a widebody to fit the 11" wheels without them sticking out or being too close to the suspension and rubbing.
I'm not familiar with Ashanti wheels so I dunno whether they're heavy or not. It also depends on a lot of things but you know what you're building and it's purpose (track, cruiser, DD...)