rj'sjeep

here is my dilemma I am going to put on 35' or 37, and tow a small tent trailer. The question is should I go with 35 I already have an ome hevyduty lift 4 inches on a 4 dr rubicon auto but I haven't done gears> Not sure I am going to either but if I do I want to be able to tow, so 35 or 37s gears 488 or 513. but I am gonna be towing. Thoughts

XTJake

Rj,

If you plan on towing with a Jeep running larger tires, you'll want to seriously consider gearing. You're already ahead of most people with the Rubicon because that gives you the 4.10 gears from the start. What motor is in your Jeep, the 3.8L or the 3.6L? The 3.8L has less power than the newer 3.6L so you'll need to get a steeper gear if you run the 3.8L.

If you plan on running 37" tires I would recommend the 4.88, and the 4.56 for the 35's. Those recommendations are for the newer 3.6L motor. Now, if your Jeep has the 3.8L I would go even steeper, I would run the 5.38 for 37's and 5.13 gears for a set of 35's.

I have attached both charts for gearing. One if for the 3.8L and the other is the 3.6L, feel free to contact me if you have any questions. I'll be happy to help!

This is for the 3.6L



This is for the 3.8L



-Zach

big dr

If I were going to tow a lot with my jeep, and not re-gear, I would stick with 35's, and my logic would be this.... 35's will get you through just about anything 37's will, and what they don't,, a good winch will. Secondly,, even if the jeep can struggle through the task of turning 37's and towing,, it doesn't mean its good for it. That is a lot of stress on engine, tranny clutch or torque converter, and ring/pinion. I think you will like the daily performance with 35's better,,, and your jeep will thank you. Just an opinion.

Maertz

5.38 gears on the auto in my opinion... I did 5.13 n wish ida done 5.38 for the hell of it. As for tires i got 35s and wish i did 37s. For towing id go 35s and 5.38s. I just towed a uhaul 1500 miles and on 5.13s n 35s some hills it struggled a ton

jeeperjkjeeper

i have a 2008 Rubi and have towed a pop-up for years with no issues. 35" Toyo MT's and 2.5" lift. I have a manual so that makes it a little nicer for towing. My buddy pulls same trailer on 37's but has 5.38's and a Supercharger with Auto Trans

nthinuf

You have a 3.8 auto, you need as much gear as you can get. Go 5.38 and don't look back. - Or just get the tires and turn OD Off until you decide on a ratio.

The consideration to 5.38's would be the distance you tow, how often you tow, and whether the load is heavy enough to warrant OD Off?

To get the OD Off rpm, divide the OD On rpm from the chart by .69.
ex - 4.10 w/ 37's = 1799 rpm @ 70. ( 1799 / .69 = 2607 rpm @ 70 with OD Off)
You'll see that OD Off rpms with 5.38's can get quite high at freeway speeds. So again, factor in the distance/duration/load weight.


I am currently running 5.38's with short 35's (measure right around 33.5 under vehicle weight) and tow a 3000+ lbs boat almost every week over the summer months. For local towing it is fine. For long distance freeway on the stretches with lots of elevation changes and OD Off, I slow down...

DGriz

Love threads like this...

I'm towing a 3000+ travel trailer with my 33" tires and 4.10 gears. We've taken it all over California during the past year and a half, but in the next 12 months or so I'll be getting a truck and 5th wheel so my Jeep won't be used as a tow rig anymore. That's also when I'll slap new 35's on it.

Would it be recommend to go with 5.13 gears now (with 33's) for towing and then, when I get the 35's, I'll be set up nice for DD and trails (no towing).

nthinuf

Gear for the tires you end up with and the 99.5% of the time you are not towing, not for the current tires or the .5% of the time you are towing. (unless you tow a LOT at high speeds...)

With a pre-'12 auto, 5.13's are fine for 33 or larger. Plug some numbers into the chart to see where you'll be with both tire choices. IF you tow OD-Off, the rpm conversion is a few posts up, so you'll know what to expect.

Jeepstin12

I have a 2012 Rubi with auto., 4:10 gears, Running 3" with 35's. pull my trailer, loaded out at 3500lbs., aka "the limit". The one thing it could have? Electric brakes. Other than that, it pulls it well. Flats, men's, does well all the way around. But, I don't pull daily. All depends on how much you are pulling. Eventually, it will wear on the driveline. I have done a 400 mile trip through the men's, loaded down, estimated 3300 lbs. and again, was good the whole trip. Engine wasn't working hard, temps stayed normal, etc.

DGriz

After talking with my wife last night about trailers, we've decided we'll run the Jeep and the smaller trailer (20' and 3,000lbs dry) for at least another year or more. So, re-gearing is definitely in the immediate plans now because we take at least 8 trips a year over some pretty substantial inclines (mostly over California mountains). My current set-up is 33" tires and 4.10 gears with a 3.8L automatic. It's tolerable most of the time but struggles on inclines. Within 12 months I intend to have 35" tires. This is also my DD but most driving is city/county roads. Not a lot of highway travel unless we are towing, and that is only at 55 to 60 mph.

After reading the posts above, it appears some think 5.13 would work for 35s and towing, while others prefer 5.38. Although I'm only running 33s at the moment, I only want to re-gear once. For those that have first hand knowledge with these set-ups, what gear ration would you recommend for 35s and towing (and why)?