Wheel Specs: Zinik Z26 chrome with black insert
Offset: +15
Back Spacing: 135mm (5.3")
Wheel Size: 20" x 8.5"

Tire Specs: Nitto Mudd Grapplers
Exact Size: 32.95 x 12.80 / 20
Approx Conversion: 33 x 12.5 / 20 = 318/52/20

Helpful tool to visualize: http://www.bigcustomwheels.com/info_specs.jsp

Of course we all know we have 6 x 139.7mm(5.5") lugs and 100mm center bore.