I have a 2012 Sahara with the stock 18" wheels, 255/70R18 Bridgestone Duelers, and 3.73 gears with auto tranny. I'm looking to purchase some 17x9 Mickey Thompson Classic II's in black along with a set of 315/70R17 Goodyear Duratracs.

The stock wheels weigh 26 lbs and the Bridgestones add another 42 lbs for a total weight of 68 lbs at each corner. The Mickey's also weigh in at 26 lbs and the Duratracs are 60 lbs for a total of 86 lbs. The upgrade nets out to an increase of 18 lbs per wheel/tire combo while providing an additional 2.3 inches of tire diameter (the Duratracs are 34.4 without load).

I was initially thinking about some Nitto Trail Grapplers, but the weight of their 315/70R17 is somewhere around 75 lbs. I've been looking at the chart below which suggests that I should probably bump up to 4.10 gears with 34/35 inch tires. However, I'm just curious what assumptions go into this chart. There has to be a huge difference in tire mass if I go with the Nittos which are a good 15 lbs heavier than the Duratracs and 33 lbs heavier than stock. Do I need to regear for the additional 18 lbs over stock from the Duratracs? I guess I'm wondering why this chart is not based upon tire weight rather than tire dimension.

Also, I'd love to see some pics or get feedback on 315/70R17 Duratracs. I'm looking at adding the soon-to-be-released 2.5" AEV lift with this wheel/tire setup.