Gearing/Towing

Hello,
I have a few questions I am hoping someone will be able to answer or give advice to.

I have a 2014 SR5 Crewmax 4x4 that has a leveling kit and 20x12 -51 wheels with 33x12.5 tires. I recently bought a travel trailer that is an Ibex 20bhs, this is a 25' trailer with a dry weight of 4,591 lbs. Loaded I am around 6,000 lbs. This trailer is quite tall and is 8' wide. I am using a weight distribution hitch, but while towing the truck has a hard time going over 50-55 mph. When I look up what the towing capacity of the Tundra is it is extremely vague 4000-10500, but I believe I have figured out that towing capacity of my truck is 9800.

Now I know I hurt my towing capabilities with the leveling kit and the wheels and tires, but should the truck be struggling this bad? Also I am currently debating whether or not I get a different truck or if I should dump some more money into my truck by adding rear air bags, and possibly 5.29 gears, different wheel and tire set up (under $5,000)? What would you do?

I have read a few posts on regearing and on towing but haven't found quite what I am looking for. As far as towing goes I have read about guys towing what sounds like trailers quite a bit larger and heavier than mine with no issues. Some of these posts claim to tow at 70 MPH with these trailers. The only way I would be able to hit 70 with my set up would probably be if the truck was in 3rd and the rpms screaming.

The regearing posts I have read sounds like it makes a huge difference and I haven't seen a post where anyone has regretted the decision. My questions about regearing are will 5.29 gears overcome the power/torque loss that larger wheels and tires create? Will my transmission be less likely to hunt for gears both while unloaded and while towing? Will it improve or worsen my MPG while towing?

Please help, I love my truck and my trailer but every time I take the rig out I get so frustrated.

 

What engine do you have?

 

I have the 5.7

 

Gear it. Had the same issue with mine. 16’ utility trailer with a 4 door rzr on it and it could only do 4th gear at 65 on flat ground. Approximately 3500lbs. I do have 34’s though.

Towed yesterday for the first time since the 5.29’s and I can do 70 in 6th and maintain up hill.

 

Put it back to stock and tow in 4th or 5th.

 

I'm assuming you're using Tow Haul & sport shift modes while towing? I rarely go past 5th when I'm towing anything. The level kit shouldn't hinder you much so I'd recommend a re-gear, and possibly, a Banks pedal monster for improved throttle response.

 

I tow an 8000# + trailer with mine and could go 90 if I had the cajones and less brain cells. Something’s up with your setup.

 

It must be debadged. Do you have the tow package?

 

I am using tow haul mode and sport shift. It usually runs in 4th and almost never hits 5th. I am using a Pedal Commander which I love for the daily drive, but haven't noticed a huge impact on the towing side.

Yes, i debadge it. I do believe it has the tow package as it came with tow haul mode, but did not have factory trailer brakes so I added aftermarket trailer brakes specifically a Tekonsha P3 and it works great.

 

Well, one less concern you have is a transmission cooler

 

I think that’s weird. Even when I had stock gears I could tow our ~7,000# 25’ travel trailer at well over 60. But, I only used 4th gear….

Mud tires aren’t helping you. Are your differentials full of the appropriate lube?

What kind of elevation are you at? Man, I wouldn’t think it would make that much of a difference, but maybe if you’re way up there?

Gears (5.29) are certainly a great addition to our trucks with bigger tires, but it’s strange that yours is struggling this much with only an inch taller tire.

Just for fun, weigh that trailer and your truck on a scale next time you’re out.

 

Kind of strange you are struggling with only 33s. We have a Jayco 264bh travel trailer and I have towed it with 3 different configurations. I also have a 2014 with the same brake controller.

Started towing with 295/70/18 and stock gears. Truck towed fine on flat ground in 4th gear, but downshifted a lot and trans temp would be at 230-240. The truck would struggle some to maintain 65mph on an incline. I averaged 8.5mpg or so towing and 13.5mpg for daily driving. For long road trips I could get close to 15mpg.

I then regeared to 529s. This was a huge improvement. I could tow in 5th on flat ground and 4th for hills while maintaining speed. My mpg did drop to 7.5-8mpg, but I had power to accelerate easily. Trans temps stayed under 200 degrees, even when climbing a hill in 4th. Daily driving a was at 12.5-13mpg.

I am now on 37s, I have to tow in 4th gear with some downshifting, but I still have good amount of power to accelerate. Trans temps still stay under 200 for 90% of towing and I peak at 210 degrees. I average 6.5-7mpg towing and 11.5-12mpg daily driving. Road tripping and driving over 80, my mpg is only around 11.

Hope that helps some

 

What's the rear axle ratio?

 

After doing a 180 miles with the 5.29’s instead of 4.30’s, gear it. Ridiculous how much better it pulls.

 

3 clicks down on that 10 speed bike. Much easier to pedal.

 

I went to a CAT Scale today and weighed the set up. Looks like I am within the capabilities of the truck. My front axle is 3380, rear axle 3800, and the trailer axles are at 4540 for a total of 11720. The door sticker on my truck says my GVWR is 7200 and the axle weights add up to 7180, so I am about maxed out there. It also says my front axle is rated for 4000 and the rear at 4150.

This was very helpful! Do you use anything in addition to the gauge on the dash to measure your transmission temp? I am thinking I am going to do the regear and put a 34x11 or 35x11 instead of the 33x12.5 and change the wheels form a -51 offset to something like a +18 offset as I believe the wheels and tires are the main issue.

Today while towing to the CAT scale it was raining, but there was no wind and I was able to tow at 60-65 more comfortably than I have previously. The truck did stay in 4th at around 3100 rpm. I do live in Idaho and tow from in town at 4800 to 5500-6500 elevation depending on where I am going.

 

If you’re not already, pull the shifter into “S” mode and lock into 4th. That will allow the torque converter to lock up once you get to speed.

there is no problem with towing the trailer in 4th at 3,000 rpm all day long. Way better to spin more rpm than to lug these motors! You will not hurt it!!!

Gearing will make a huge difference, but is expensive. Only you can decide if it’s worth it…

Going to a narrower tire will help, but going taller will hurt. Wheel offset will have little to nothing to do with your mileage, but will have other positive effect.