Can someone explain how towing capacity works?

I have a 2.7 DCSB, and Toyota says my towing capacity is 3,500 lbs. I'm trying to understand exactly how towing capacity works. I know my capacity means that I can haul something behind me that weighs 3,500 lbs, but if I've got really good wheels on my 3500 lb trailer and I'm on level ground, then the lateral force I have to exert to get it moving isn't 3,500 lbs, but something considerably less. In fact, a strong, strapping lad would be able to move it by hand. I would only have to exert that much force if I was trying to lift the trailer straight up. As the grade increases from level to steep, then I have to use more force to keep the trailer moving.

So when Toyota says that my 2.7 DCSB can haul 3,500 lbs is that taking into account the possibility that I might need to climb some steep hills while doing so? If I were only ever driving on perfectly level roads would I hypothetically be able to haul more than that?

Also, I know some Tacomas come with a towing package. Is there more to the towing package than a trailer hitch and wiring? A few dealership pages out there seem to imply that a 2.7 with a towing package can haul 6,400 lbs but I think they're actually talking about the V6 without saying it.

 

Towing?

 

Its basically this
http://www.trucktrend.com/how-to/towing/1502-sae-j2807-tow-tests-the-standard/

 

Seriously, I know I know I am a joker etc, but how this damn truck holds down speed down, under max load, blows my mind. Using Sport, manual shift, butt pucker..etc. I don't think I can really explain the feeling the first time going down one of those Utah mountain hill with 6,500...er plus strapped to the back of this Tacoma. I did never mention, Salt Lake traffic and Las Vegas Traffic. Butt pucker factor was 10.

 

2.7L on 35’s for the win. Bro, you pretty much can’t hurt that truck, even if the 7k load feels like it’s going to rip your frame in half.

 

Stopping is a huge factor. That strapping lad might be able to get it moving. But how long to stop it?

 

Hey, to be fair, he asked about towing, not stopping.

 

I should say I have the 3.5 V6 maybe...

 

Anyway, it will tow way more than you think it would.

 

Trailer brakes are a thing.

Every vehicle I've owned makes a distinction between towing capacity with and without trailer brakes.

 

Towing and pulling aren't the same thing. Most trucks will PULL the rated tow capacity easily, even on inclines. The limiting factor 95% of the time is the weight the trailer adds to the trucks suspension. That is the payload rating. When you see published tow ratings that assumes a stock truck just as it left the factory with only a 150 lb driver in the cab. No other weight from passengers or cargo is included. In the real world the Tacoma's with V6 engines rated to PULL 6500 lbs will have their trucks overloaded at around 4500-5000 lbs.

This is true even with 1/2 ton and 3/4 ton trucks as well. When you see Ford advertise their 1/2 tons will tow 12,000 lbs that means certain Unicorns they build will do so with only a skinny driver in the cab. Most 1/2 tons run out of payload with anything over 7000-8000 lbs, and some of them will actually tow less than a Tacoma.

Think of a see/saw on a playground. When you start adding weight to a trucks trailer hitch you add weight to the rear axle, but at the same time you reduce the weight on the tires on the front axle. You'll never add enough weight to actually pull those front tires off the ground, but if you're running over the trucks rated payload you do reduce the amount of weight on the front axle enough to have a negative effect on the trucks steering and braking. Remember, the front wheels do about 80% of the braking and 100% of the steering.

Some guys modify their suspension so their trucks are sitting level even when overloaded. This doesn't solve any problems, it just hides them. The truck is still overloaded. If the truck is sitting low in the rear that is a visual cue that you're overloaded.

How the trailer is loaded is HUGE. If you put too much weight on the front of a trailer it increases the weight on the trucks suspension. Move too much weight to the rear of the trailer and they are dangerous to pull. Loaded correctly 13-15% of the trailer weight is on the trucks suspension. That would be 450-525 lbs with your 3500 lb trailer. Could your strong strapping lad pick up the 450-525 lb trailer tongue to maneuver the trailer?

Payload ratings for trucks are all over the place. You can't depend on the specs in charts or online. Every truck is different and it can vary considerably. There is a sticker on the drivers door jamb of your truck with the payload on it. On Tacoma's some are as low as 900 lbs, some are over 2000.

My Tacoma is rated at 1200 lbs. I have a 180 lb cap on mine. I weigh 220, my wife 140. We've already used up 540 lbs of available payload before adding a trailer. I only have 660 lbs left for a trailers tongue weight. That means that a trailer over about 4500 lbs will overload my truck even though my tow rating is 6500 lbs. I could technically tow 6500 lbs. But I'd have to leave my wife at home and carry nothing else.

You'll just have to check your payload rating, but your truck is probably one of the 5% that won't run out of payload before you run out of tow rating. But you still have to be careful. Remember, a 3500 lb trailer is already adding 450-525 lbs to your truck. If you have 4 skinny 150 lb people riding in the cab that is another 600 lbs. Four big adult men could easily be 800-1000 lbs in addition to the tongue weight. And that doesn't include any cargo or gear carried in the truck or truck bed.

 

Nice write up, should be an auto reply every time this way misunderstood subject comes up!

 

Lol you have to stop right?
Tou might have to swerve around something right?
You might have to make an emergency stop right?
The wind might blow hard right?
You might have to go up a hill right?
You might be stuck in bumper to bumper traffic at 95 degrees right?
And lastly, you might have to speed up in a limited distance to merge into traffic right?

Yea, 3500 means a lot more than pulling force on level ground.


BTW, in order to maintain 70 mph on level ground with no load, trailer or anything requires about 73 hp according to my calculations. This is because of rolling resistance and aerodynamic drag. Throw a boat or box trailer on there and you easily double that. How many hp's does that engine have?
There's your answer.

 

Good job. Combine my post and yours and you have a complete explanation.

 

Thank you! This is exactly what I was looking for. I had forgotten to ask about how payload in the bed affects towing capacity but you answered that as well.

Is a towing package more than just a hitch and cable? Is it additional suspension or something else as well?

 

here’s what i don’t quite understand: as far as the frame, axles, brakes, transmissions, my understanding is that all new tacomas are relatively the same. it’s the reason the payload is greater on the 2TR trucks; the engine (and less amenities) is lighter and all the vital underpinnings are the same. less weight, more carrying capacity.

but where could the (nearly half) 3500lb tow rating come from then, other than the straight up lack of horsepower? if a V6 (wItH dRuM bRaKeS) can stop with a heavier trailer... the 2.7 has the same brakes (afaik).

obviously towing a decent load up a 7% grade at 70mph ain’t gonna happen with these 2TR trucks, i think we all know that already. i always assumed the lower tow rating was for highway safety and the typical speeds we see on interstate highways.

 

Transmission cooler, engine oil cooler are the big ones. I think the wiring is also beefed up in some way.

 

https://www.youtube.com/watch?v=JQQzNJzllDI
https://www.youtube.com/watch?v=5RbqPaqtpuI
https://www.youtube.com/watch?v=6mW_gzdh6to
https://www.youtube.com/watch?v=w9Dgxe584Ss

 

Read what hiPSI said in post #14 -- empty truck requires 73 hp, the 2.7 engine only has 159 hp available. You need to be able to get out of your own way.

 

The transmission, the engine...
Sure, the truck itself can pull more but not with that engine and transmission.