Confused about gears
04-01-2012, 03:05 PM
#11
JK Newbie
Join Date: Dec 2009
Location: Jacksonville, Florida
Posts: 45
Likes: 0
Received 0 Likes
on
0 Posts
RSTRICK is spot on. I also have a 2010 JK Sport, 2 door auto, and just put in 5.13 Yukon gears. I chose the 5.13 after much research and found it the best for an automatic with 35 tires. I am very pleased with the performance of the new gearing both in city and highway driving, and use my Jeep as a daily driver. Blue Project, I highly recommend going with 5.13 for your rig. You will not regret it.
04-01-2012, 03:17 PM
#12
JK Junkie
Join Date: Jul 2008
Location: Lakewood, OH
Posts: 3,017
Likes: 0
Received 0 Likes
on
0 Posts
Tire
Gear Ratio
Conversion;
Tire Vs Ratio
Size 3,31 3,42 3,55 3,73 3,91 4,11 4,27 4,56 4,88 5,13 5,29 5,38 5,71 6,17 7,17
30 2410 2490 2584 2715 2846 2992 3109 3320 3553 3735 3851 3917 4157 4492 5220
31 2332 2409 2501 2628 2755 2896 3008 3213 3438 3614 3727 3790 4023 4347 5051
32 2259 2334 2423 2546 2669 2805 2914 3112 3331 3501 3610 3672 3897 4211 4894
33 2191 2263 2349 2469 2588 2720 2826 3018 3230 3395 3501 3561 3779 4083 4745
34 2126 2197 2280 2396 2512 2640 2743 2929 3135 3295 3398 3456 3668 3963 4606
35 2065 2134 2215 2328 2440 2565 2664 2845 3045 3201 3301 3357 3563 3850 4474
36 2008 2075 2154 2263 2372 2493 2590 2766 2961 3112 3209 3264 3464 3743 4350
37 1954 2019 2095 2202 2308 2426 2520 2692 2881 3028 3123 3176 3370 3642 4232
38 1902 1966 2040 2144 2247 2362 2454 2621 2805 2948 3040 3092 3282 3546 4121
39 1854 1915 1988 2089 2190 2302 2391 2554 2733 2873 2962 3013 3198 3455 4015
40 1807 1867 1938 2037 2135 2244 2331 2490 2664 2801 2888 2937 3118 3369 3915
44 1643 1698 1762 1851 1941 2040 2119 2263 2422 2545 2626 2670 2834 3063 3559
A Ratio of 3.73 with a 32 inch Tire has great fuel economy, but poor torque.
A Ratio of 4.11 with a 33 inch Tire is good as a daily Driver.
A Ratio of 5.29 with a 35 inch Tire has Great Torque, but poor fuel economy.
This is just a quick chart I threw together showing what Your RPM's will be at a certain Tire Size vs Gear Ratio, but as previously posted,
You can find a wealth of information on the net.
A simple formula for the correct gear ratio is this:
..........................New Tire Size x Old Gear Ratio
New Gear Ratio = ―――――――――――――――――
..................................Old Tire Size
Hope this helps some.
Gear Ratio
Conversion;
Tire Vs Ratio
Size 3,31 3,42 3,55 3,73 3,91 4,11 4,27 4,56 4,88 5,13 5,29 5,38 5,71 6,17 7,17
30 2410 2490 2584 2715 2846 2992 3109 3320 3553 3735 3851 3917 4157 4492 5220
31 2332 2409 2501 2628 2755 2896 3008 3213 3438 3614 3727 3790 4023 4347 5051
32 2259 2334 2423 2546 2669 2805 2914 3112 3331 3501 3610 3672 3897 4211 4894
33 2191 2263 2349 2469 2588 2720 2826 3018 3230 3395 3501 3561 3779 4083 4745
34 2126 2197 2280 2396 2512 2640 2743 2929 3135 3295 3398 3456 3668 3963 4606
35 2065 2134 2215 2328 2440 2565 2664 2845 3045 3201 3301 3357 3563 3850 4474
36 2008 2075 2154 2263 2372 2493 2590 2766 2961 3112 3209 3264 3464 3743 4350
37 1954 2019 2095 2202 2308 2426 2520 2692 2881 3028 3123 3176 3370 3642 4232
38 1902 1966 2040 2144 2247 2362 2454 2621 2805 2948 3040 3092 3282 3546 4121
39 1854 1915 1988 2089 2190 2302 2391 2554 2733 2873 2962 3013 3198 3455 4015
40 1807 1867 1938 2037 2135 2244 2331 2490 2664 2801 2888 2937 3118 3369 3915
44 1643 1698 1762 1851 1941 2040 2119 2263 2422 2545 2626 2670 2834 3063 3559
A Ratio of 3.73 with a 32 inch Tire has great fuel economy, but poor torque.
A Ratio of 4.11 with a 33 inch Tire is good as a daily Driver.
A Ratio of 5.29 with a 35 inch Tire has Great Torque, but poor fuel economy.
This is just a quick chart I threw together showing what Your RPM's will be at a certain Tire Size vs Gear Ratio, but as previously posted,
You can find a wealth of information on the net.
A simple formula for the correct gear ratio is this:
..........................New Tire Size x Old Gear Ratio
New Gear Ratio = ―――――――――――――――――
..................................Old Tire Size
Hope this helps some.
https://www.jk-forum.com/forums/show...76&postcount=4
04-01-2012, 03:59 PM
#13
JK Super Freak
Now for strength ... meh I went 5:13's for strength reasons as 5:36's on a D44 front end is sketch with a teeny pinion. Now on a Dana 30 front the same holds true for 5:13's so some opt for 4:88's for the same reason. in terms of transmission options 6 speeds usually go 4:88's anyhow due to enherent gearing
04-01-2012, 04:39 PM
#14
Super Moderator
Join Date: Jun 2011
Location: Hendersonville, Tennessee
Posts: 11,043
Likes: 0
Received 83 Likes
on
75 Posts
Originally Posted by RSTRICK
If you read the op he said he drove with OD off before the gear swap. I love my 5:13 Yukon gears and it is my DD it sees a mix of two lane, interstate, and city driving. As well as a weekend warrior. It sees 75 mph on a daily basis I avg 17 mpg.
04-01-2012, 04:52 PM
#16
JK Super Freak
Join Date: Oct 2007
Location: Parksville, British Columbia
Posts: 1,030
Likes: 0
Received 0 Likes
on
0 Posts
RSTRICK is spot on. I also have a 2010 JK Sport, 2 door auto, and just put in 5.13 Yukon gears. I chose the 5.13 after much research and found it the best for an automatic with 35 tires. I am very pleased with the performance of the new gearing both in city and highway driving, and use my Jeep as a daily driver. Blue Project, I highly recommend going with 5.13 for your rig. You will not regret it.
04-01-2012, 04:53 PM
#17
JK Super Freak
Thread Starter
Join Date: Jan 2011
Location: Cape Cod
Posts: 1,531
Likes: 0
Received 0 Likes
on
0 Posts
I'm starting to understand some of this. I asked some of the vendor's a while back about this and they said 4.56's. Why have I been told if I changed my gears I couldn't run the highway? How would 4.88's vs 5.13 fair against 35's on the highway?
04-01-2012, 05:00 PM
#19
JK Super Freak
04-02-2012, 03:50 AM
#20
JK Super Freak
Thread Starter
Join Date: Jan 2011
Location: Cape Cod
Posts: 1,531
Likes: 0
Received 0 Likes
on
0 Posts