I know their is a lot of post on this as I read most of them so here my question. I see that with a auto and 35s everyone says 5.13s but the ring and pinon is getting small on the d30. I see on the charts that their is only about 100 rmps difference between 4.88 and 5.13s at 70mph so are 4.88 that much stronger to make it worth giving up the little extra power of the 5.13s?

I use the 4.88 with my 34" tires with out issue, or at least know that I can tell. I averaged 15.5 mpg on a 4500 mile trip out west to Utah back in 2010. And that includes a couple hundred miles off roading in 4 low in Moab too. Most of the time on the highways was running 75 to 80 mph. And, I was towing my expedition trailer too. Overall I think that's pretty good for 4 people in a loaded down JKU with 1500# of trailer.

Hope that helps

I dont believe the size doesnt start to change until you hit the 5.38's. I have 5.13 in mine and Ive broke 4 axle shafts, one carrier, and a lock rite locker without any damage to my ring and pinion. I think youll be fine