the alltitude is our problem. i was driving from 4k feet to ovet 6k. not to mention it was humid so the density altitude is even worse. i drag my Z06 and here my times are typically .7 slower than they would be at sea level.

 

im running 4.10 wth 37x13.50x16 and just used the hypertech programmer last week. i dont see a boost in power but my engine seems to not bog like it did before. i can over the bridges here in florida wth big humps and i dont even go over 2000 rpm where as before was well over 4000. i havent been on big incline like those of colorado or mountains but i did see certain improvements after reprogramming. on the automatic, once u reprogram, the shifting is alot smoother and doesnt rev up as high before shifting. IMO the money was well worth it. maybe that should be a consideration for u.

 

that cool about the 37s.....my buddy wants to upgrad in tire size....what type of milage are you getting with 37s and a auto....i am getting 16ish steady on highway....what is the difference with the auto...thanks

 

I have 35's auto and the hypertech, using premium fuel and settings greatly improves the highway driving compared to the regular setting

 

I made that same run this weekend....I hit 6th briefly a couple times. Mostly in 5th with an occasional burst in 4th but I have a 2 door not a 4 door so I am sure that the weight plays a factor.
Either way JK's are not the only ones struggling on that hill....I passes several OLD hondas, fords and other $hit boxes with 4cyl that were doing much worse that we are.

 

Good to know, I have a similar set-up. I'm probably going to do a cat-back soon for aesthetics and function more than anything. If it gets me 0.25 more MPH/gallon and 2 HP it would be a bonus. The programmer may be in my future too

 

I have an Unlimited Rubicon with 35's. Went to 5.13's thinking the same thing. Problem is the computer still thinks everything is stock. Installed the Hypertech Max and WOW! Big improvement. Then added cold air intake, little more improvement. Then added Magnaflow, little more improvement. Overall I'm very happy. Can pull any pass in Colorado @ 70mph easy and still average 18mpg.

 

Actually the Rubicon comes with 4.10's and 32 inch tires.

 

Wow, that's not good. I made the same trip last weekend and had no probs with my 3.73s and 33s. Used just over 1/4 tank.

Off topic-did you get stuck up there because of the rains? Fortunately, we didn't. Didn't get to do any fishing though because of the damn rain.

 

Actually, if we want to get technical, once on the rim the rubi tire is barely a 31 (that where the stock computer setting is at) and my 305/70R/17 (34) are a little over 33" and most 35's are over 33.5".