Understanding Cat Scale Numbers

I have a 2019 Tundra Platinum that I am going to start pulling a travel trailer with. I installed a weight distribution hitch and went to the scales and here is what it showed.

Truck only Steer axle 3580
Drive axle 2800
gross 6380

Truck hooked to trailer without distribution bars engaged
Steer axle 3320
Drive axle 3760
Trailer axle 4940
Gross weight 12,020

Truck hooked to trailer with bars engaged
Steer axle 3540
Drive axle 3380
Trailer axle 5080
Gross weight 12,000

Max weight for truck is 7200 Payload for truck is only 1100
Gross for trailer is 6000

Trailer pulled good I thought. I have no idea if its set up properly. Any way to tell the tongue weight by those numbers?

 

I think you have the WDH dialed in. Did you do the install and adjustment?

 

Yes I did it myself. Watched lots of youtube videos. I towed it a couple of hundred miles and at 60-65 mph seems fine. I'm sure when the wife starts packing for camping things may change. She will want to bring everything we own. Might need a bigger truck then haha.

 

Thanks. That is what I was thinking but was not certain.

 

Mine does that too. Once fully loaded check the scale again. The WDH is supposed to be adjusted after you are packed up. Unless you pile a bunch of heavy objects near the tailgate you should still be much better adjusted than 99% of those on the road.

Kudos for taking the time to set it up right. Now, watch those transmission temperatures or just keep it in S4. I can't prove you use any more gas by staying in S4 vs S5 or drive but my Scangauge tells me the transmission is much happier in S4.

 

Thanks. I probably will not be able to load much of anything in the bed of truck. I'm kind of OCD so all the numbers have been stressing me out a little bit.

 

It's refreshing to see someone doing it right. Instead of the "Can my Tundra pull this 14,000# fifth wheel?". Or even worse the ones that do pull a much larger trailer than they should and come here bragging about it.

Maybe @ColoradoTJ will have a forum award for you!

 

Thanks. I'm trying. I have the thing plugged into my OBD port and transmission pan temps were around 219 degrees in S4. I am installing the transmission cooler on Saturday in hopes of getting the temps down. Then I will re-weigh everything once the wife loads all of her stuff. LOL.

 

This is great!
You asked about tongue weight. Here is how to figure it out.

Unloaded vehicle weight is 6,380 - this is easy
Now with the trailer hooked up add the drive and steer axle weights - 3,320+3,760=7,080
Tongue weight is the difference between the two - 7,080-6,380=700 pounds

What is that 700 pounds doing to the truck?
- It is adding 960 pounds to the drive axle (3760-2800)
- It is removing 260 pounds from the steer axle (3320-3580)
It is the removal of the weight on the steering axle that is concerning. So you add weight distribution.

What has this done for you?
- It has transferred 140 pounds of the tongue weight back to the trailer axle (5080-4940) - This is no longer carried by the truck!
- It has removed 380 pounds from the rear axle of the truck (3380-3760) leaving you with 580 pounds on the rear axle.
- It has transferred 220 pounds to the tongue weight back to the front axle (3540-3320)

OK, so those numbers don't seem to add up to anything. I have 700 pounds of tongue weight. None of those numbers say 700 pounds. Where and why?

I will try to make it simple.

In the first scenario (no weight distribution) you have 700 pounds pushing down on the hitch. Since the hitch is not right over the the rear axle you truck acts like a lever and the rear axle is the pivot point. The front picks up and the rear squats down. Since the truck is supporting 700 pounds, whatever you take off the front axle is added to the rear axle.

Now you add weight distribution.
You move (distribute) 140 pounds to the trailer. This is 140 pounds that your truck no longer needs to carry.
You move (distribute) 220 pounds to the front axle. Now you only taking 40 pounds off your steer axle. This is much better!
Your truck is carrying 560 pounds of additional weight.
Your front axle is still 40 pounds light.
This means that your rear axle is carrying 600 pounds. Or 580 pounds depending on if you believe the 12,000 or the 12,020 (small error in the scale)

Your tuck will squat some. You do have 600 pounds on the rear axle.

Your setup is not bad. Your steer axle is nearly the same as it was before you hooked the trailer up. This is generally the goal.
You could add a little more spring in the weight distribution but IMO you are in good shape. And you said it drives great. I am not surprised.

Adding more spring will continue to move weight to the trailer axle as well. This will help take weight off the truck if you are looking to put more stuff in the truck. Some would argue that you need to do this until there is ⅓ of the trailer tongue weight moved to each axle.

 

Thank you. This has been very helpful. Love this site. I have a pretty good understanding now.

 

You have trans temp of 219 and your coolant temp is probably 200.
You have a liquid to liquid cooler/warmer on the side of the trans.
Seeing a 20 degree difference between these fluid temps is what I would expect. IMO it is operating as Toyota intended. They want the trans temp to mirror the coolant temp.
If you run your pan temps below your coolant temps, you are warming and cooling fluid at the same time. Something feels off about this. I guess this is why there is thermostat on the trans cooler. Don't expect trans temps to stay below 185 to 190. If I recall correctly the thermostat is 185 and there is not a huge amount of fluid pumped through this thing.

Let the flames fly. But anyone who is running the Toyota thermostat and claims to have pan temps that are lower than the thermostat temp should be questioning why.

 

Ok yes while towing that trailer the transmission temp was between 207-223 or so. Climbed a few good sized hills. Coolant temp was 198-202. I bought that one from Genuine Cooling Systems. Hmmmm so maybe I should not put it on? I just had a 2020 highlander transmission fail at 79,000 miles. A little paranoid now. But that is apples to oranges 8 speed vs 6.

 

A cooler will not hurt anything at all. I would not discourage you from doing it. It is a good thing.
Just know that you will still likely see transmission temps right around 200 degrees. Physics will not let it get cooler than that.

 

I have a 21 with 35K miles of which 12,000 are towing a 6,000# GVWR trailer. I haven't done the trans cooler mainly because of the stank eye my dealership gave me about warranty on the transmission should a failure occur. I did a drain and fill at 22K and another last week. The second D&F got a sample and sent to Blackstone. If they like my schedule I'll stick with it.

 

This is as designed by Toyota. The owner's manual will back this up.
You will not use more gas in S4 at the same speeds.
It is better for your engine and transmission in S4.

 

In towing mine usually settles in about 210ish pan temps. I would love to have one but the dealer even balked at me paying them to do the labor and use OEM parts.

 

What trailer do you have?

 

This is worth a read IMO. My setup does not transfer all of the weight back to the front axle, but according to myth #5 here that may not be a bad thing depending on what manufacturer you ask.

https://askthervengineer.com/the-big-7-misconceptions-about-weight-distribution-hitches/

 

I have a 2020 Grand Design 21BHE. I think total length is right at 25 feet

 

Perfect choice for the Tundra. Enjoy the lifestyle.

 

I love hitting the cat scales and have been using now for the past few years with my RV and a couple of things I have learned that I find useful. First time I paid on site and was a bit of a hassle, so I downloaded the app and so easy to use. Pull up to the scale, put the number of the cat scale (there by the intercom) it charges your CC that you have already uploaded, so you don't have to talk to the lady in the box that I can never understand anyway. You then receive the email with the spreadsheet which I later print for my records and done, too easy. Many times, as long as no one is behind me, I will pull just my truck off the scales and disconnect the camper and see my actual camper weight and tongue weight. This only cost $3 since you are doing another weighing and within 15 minutes.

Another quick and somewhat accurate way to determine your tongue weight is to multiply your camper weight by 10-15%, most do 12%, I'm closer to 13%. My camper has a heavy tongue weight of around 1000lbs and 7500 fully loaded. So I'm a bit concerned coming over to this new 2024 Tundra as it has only 1300lbs of payload and the F-150 I'm leaving has 1760...giving up 460lbs is a big loss. I will already have my payload maxed out just by my wife and I climbing aboard and the camper hooked up. I don't like going over the numbers but looks like I will be pushing the envelope by a few hundred lbs. I see where the front and rear axle rating of this tundra are 4080 so I will be paying very close attention to what those numbers look like.

 

Here is another little bit of information. When I bought the trailer from the guy he had a Husky WHD that he included with the trailer. He also had a generator mounted to the tongue above the battery and propane tanks. I could tell it felt heavy so I drove to the scales just to see what it weighed.
Steer axle was 3480
Drive axle was 3820
Trailer was 4980
Gross 12280
I got home took the generator and mount off and bought an equalizer WDH and it seems to have helped.

Thanks and yes I got the app. That does make it easier. That is exactly where I am at with my payload. The wife and I put it really close just getting in the cab but man I love this truck. So fun to drive.

 

Yeah I've seen folks with those gens loaded up front like that and I always thought to myself that has to be adding a ton to the tongue weight. My camper also uses 2 30lb propane tanks and that is a lot there. I believe I'm going to remove both in the summer and run one 20lb tank. I modded my Honda 2200 to run off propane and so it is nice to have those tanks to run it and not carry gas that can tip over and spill......ask me how I know

 

Just weighed in with full tank of gas and me ...'21 SR5 CM 4x4. Leaves me 900 lbs payload

 

numbers only matter if you check them

with a topper and decked drawers, I’m at nearly 6700lbs on a stock truck…

 

Ya, I'm really curious how she weighs out when we we're all packed out with the RV in a few weeks. I'm not worried just curious with all the chat about exceeding Tundra's weight capacity. I'm pretty sure we're going to be under my 900lbs payload as I'm weighing everything we put in bed and cab and created a spreadsheet in excel.