I got my 5.13 Superior Gears installed, and have an Unlimited Rubicon with an Automatic. I'm running 35x12.50's on it right now. Honestly it is nicer to drive both in town and on the freeway with the 5.13's and 35" tires than it was with the 4.10's and factory 32's.

Using a GPS and cruise control, here is a list of my Actual speed, RPMs, and what the speedo was reading (very close guesses on the RPMs and Speedo due to the sucky gauges with no incremental markings.) The cruise keeps a constant speed now even on inclines, and it's a lot more peppy to drive around town. It feels very at home driving highway speeds now. It was fine before, but would downshift on inclines.

GPS Speed --- RPM --- Speedo reading
------------------------------------------------
50 MPH --- 1750 RPM --- 47 MPH
55 MPH --- 1900 RPM --- 52 MPH
60 MPH --- 2100 RPM --- 56 MPH
65 MPH --- 2250 RPM --- 61 MPH
70 MPH --- 2450 RPM --- 66 MPH
75 MPH --- 2600 RPM --- 70 MPH
80 MPH --- 2800 RPM --- 75 MPH

Another bonus, before the swap, running the 35's and 4.10 gears, I was averaging 12.5-13.0 MPG. So far I'm getting 15.5-16.0 driving the same roads as before. If you are even considering doing a gear swap, I say go for it...you will be very pleased with the results.

 

Thanks for the info. I am also running 35"s with an auto. I drive 150 miles a day. I can't wait to change the gears!!!! The shifting and searching for gears and not holding 80 mph is driving me NUTS

 

Cool. Now I know I will go with 5.13 gears, rather than 4.10. Thanks.

 

You think 5.13's is a better way to go than 4.88's? It would be nice to get overdrive back.

Clackey at 80 you'll be running some high rpms.

 

I wonder how much of this will hold true with 37s... Is the 5:13 a better all around gear then a 4:88 for an auto Rubi?

 

^ beat me to it...

 

5.13's is definitely the way to go with 35's + and an Automatic. I couldn't be happier with them. Let me dig up a chart I made a while back and I'll post it shortly. I'll see how close it was to my actual readings too.

 

OK here's the chart I made a couple of months ago when I was trying to make my decision. Notice that at 80 MPH you are only going to be turning 135 RPM more with the 5.13's than you would have with the 4.88's. That right there is what made the decision for me to use 5.13's. Looks like my chart is almost dead-nuts on to what my actual readings are too.


Here's a quick comparison for an Automatic with 4.10 and Stock Rubi Tires vs 4.88 and 5.13 with 315/70/17 tires.

All RPM's are in Overdrive (4th gear)

4.10's with 255/75/17 (stock Rubi tires)
55 MPH = 1631 RPM
60 MPH = 1779 RPM
65 MPH = 1927 RPM
70 MPH = 2075 RPM
75 MPH = 2224 RPM
80 MPH = 2372 RPM

4.88's with 315/70/17
55 MPH = 1811 RPM
60 MPH = 1976 RPM
65 MPH = 2140 RPM
70 MPH = 2305 RPM
75 MPH = 2469 RPM
80 MPH = 2634 RPM

5.13's with 315/70/17
55 MPH = 1904 RPM
60 MPH = 2077 RPM
65 MPH = 2250 RPM
70 MPH = 2423 RPM
75 MPH = 2596 RPM
80 MPH = 2769 RPM

I think I'll be going with the 5.13's.

 

that helped alot... 5:13s it is for me...I was already leaning towards that anways... but now I am certain , thanks

 

80mph huh, seems little fast for 3 or 4 inch lift and 35" tires too me.