JK Rubis come stock with 32 inch tires. With no lift, I would go with 265/70R17, 275/65R17, or 275/70R17 on 17x8 inch rims. All 3 of these sizes are around 32" tall, and are between 10.5 & 11 inches wide.
I'm not sure about the ideal backspacing on a JK. Most TJ guys go with around 4" of backspacing.