Duster wheel size with mini tub

Anyone running 18x10 reads on their dusters / demons? Curious how wide of a tire I can run with offset springs and stock wheel well and with a mini tub if I need to go that route.

So far with my measurements I can get away with a 275 or 285 for sure but wondering if a 305-315 would fit with a mini tub. Is the spring location the issue or the inner wheel well to running the wider tires.