Bryan H

Gear recommendations and questions are obviously popular discussion points on the forum....but I think I have a slightly different situation that 'might' change the optimum gear selection.

I have an '11 Sahara JKU, auto. I'm currently on factory tires, but will eventually end up with something between 33-35" tires. Definitely nothing larger. Here's my problem. I frequently tow a 2800 lb camper. While towing, I disengage OD in order to maintain a speed between 60 and 65 mph. With my factory 32's, I'm running about 2650 rpm with OD disengaged. Let's say I step up to a 34" tire (to split the difference of 33's and 35's). That will drop my rpm to 2500. If I regear my factory 3.73's to the ever popular 5.13's, I'd be at 3400 rpm. Way too high for me over prolonged distances. Even with 4.88's, I'd be at 3300 rpm. So, I'm wondering if 4.56's might be a better option for me. That would put me at 3050 rpm while towing, and somewhere just north of 2,100 rpm when cruising without the camper and with OD on. Certainly, the 2,100 rpm isn't optimal, but I'm wondering is this is perhaps the best option for me since I definitely want to maintain my towing capability (and towing in OD is not recommended).

TIA for your insight/experiences/suggestions/name calling/etc.!

renpia

Those RPMs your quoting seem really high. Is that your estimate with OD off, towing, going up a hill? With the 5.13's on a flat surface normal driving doing 65 mph, I got around 2300-2400 tops. Now Im not towing anything heavy, but would towing make the RPMs go that high?

ronjenx

The rpm would be high if the power demand was such that the torque converter wouldn't lock up.

DGriz

I hope this isn't considered a hijack but I'm really interested on how the tire size/gear ratio will work too. For me, however, I'm using my Rubicon with 4.10 gears to pull a 3,000 lbs. travel trailer. I'm going to 33" Duratracs later this year and really trying to understand how it will effect my towing and what gears I should consider. I'm perfectly happy with the 4.10 while on flat land (and I always take OD off), but when pulling up a steep incline I've dropped all the way down to 40 mph. I can only assume those larger tires will make it even tougher so where's the happy medium? Personally, I'll be OK with higher RPMs on flat land in order to give me more power on the inclines.

Bryan H

That is OD off at 65 mph (converter locked). That's why I'm so torn.

Surf City Dan

I think you nailed it on the head.. 456's with OD off will put you at near optimal RPM's. Especially for towing..

nthinuf

Option 1
Gear for the 95+% of the time I am NOT towing, and keep the speed down when OD Off. (like you, I prefer OD Off when towing heavy loads).

Option 2
Gear for the less than 5% of the time that I AM towing and be miserable with the performance the other 95% of the time.


I would rather be happy (geared correctly) for the majority of my driving time, rather than gear specifically for towing.

Bryan H

I think you're right UNLESS any of your towing is done over long distances. That could be miserable (either really slow or really high rpm).

I may also go with a RIPP package, so I'm hoping that would make up for the lack of performance with 4.56.

nthinuf

Probably not a right or wrong answer (or at least not a right answer that would work for everyone), but your first post indicated speeds down between 60 & 65 for towing, not up at 70-80+. Lower speed towing should lead you to gear as noted above.


My experience: I have a 4door auto with trans cooler, a 4" lift and 35's, running 5.38's, and tow a boat that is pushing the 3500lb limit. I realize that boats are fairly aerodynamic as compared to travel trailers, but other than the normal "this engine is gutless" comment, I have no issues with towing it at all. On a recent 14 hour trip from texas back up to colorado, I was easily holding 75-80 (OD On) on a few of the flatter stretches. Though as noted, I prefer od off towing, and most of the trip is hilly and/or windy, so the majority of it was OD Off down around 65.
Did the same trip with 5.13's and a 'fully' loaded 6x12 enclosed uhaul trailer. Harder pull than the boat, but no issues being OD Off the entire trip.

Another point in favor of not under-gearing is that I have found myself on a few steep low-speed hills (in addition to boat ramps) that I could not move forward on. Had to not only go into 4wd, but down to 4low. Not an issue of 2wd traction, just did not have the grunt to move.

Anyway, just a heads-up to think about the big picture so you don't make a multi-thousand dollar mistake. Look at 'all' of your driving, not just the towing time, before you make your decision.

Bryan H

So at 65 mph with your 35's and 5.38 gears, you should have been running around 3500 rpm with OD off. That seems really high for sustained driving. It wasn't an issue for you?