How much excess towing capacity

[FCStreamer]

I think the payload and towing limits have been limited enough by the lawyers. If my truck says it can haul 8000 lbs, then I am going to haul up to 8000 lbs. Not 8001, but yes to 8000. And if my payload is 1600, then I am going to load 1600. I think that if they posted those numbers, it was for a REASON. I will stick to those numbers rather than trying to impose some self-defined limitation.

[A W Warn]

Originally Posted by PSU1981

We have a 2015 27FB FC that I pull with a 2015 Tundra with 10,000 lbs towing capacity. The cloud has a UBW - dry weight around 5800 lbs - With Max gross weight of 7600 lbs. Anyways how much excess towing capacity should I have to say pull thru the Rockies? Be able to tow anywhere in the U.S. ?

Thanks,

Glenn

My opinion is that your truck is adequate.

However;

You also need to consider the Gross Combined Weight Rating of your tow vehicle, when calculating whether or not your vehicle combination is within specs.

At some point, as trailer weight increases, payload in the tow vehicle has to be decreased. At maximum trailer weight, calculations using the tow vehicle manufacturer's specs will show that payload will be limited to the weight of a driver.

At some point, as you carry additional payload in the tow vehicle, the actual towing capacity is decreased below maximum capacity.

My suggestion: Weigh the vehicles! Then, DO THE CALCULATIONS!
It's the only way to know for sure if your loaded vehicles are within specs.

[dkottum]

My problem with ratings is they give no consideration for differences in trailer design, aerodynamics, center of gravity and type of suspension. Or how it's loaded, correct weight and balance. This makes a difference.

They make no consideration for a weight distribution and/or sway control/sway elimination hitch, and the quality of setup. This makes a difference.

There are differences in the design of possible tow vehicles that give those more closely matched to the trailer being towed, advantages over tow vehicles that greatly exceed the needs of the trailer being towed. Too much excess capacity may lead to a truck that is more prone to handling issues in emergency maneuvers, and more likely to be unstable when it happens. As I understand it.

For these reasons we have no reservations about choosing our tow vehicle that is closely matched to our particular Airstream, extended travel destinations, and load requirements. Fifty years of travel defines our requirements. We have the easiest towing, most stable travel trailer hitched properly by a rock solid w.d. hitch.

We have plenty of excess quality in our towing combination if not excess ratings, it is intentional and we believe a high quality, very safe truck, hitch and trailer in all travel conditions.

The truck's fuel economy, drivability and very comfortable ride are also considerations and a bonus.

[guskmg]

Just a word of caution. When you add up your weights be sure an use actual scale weights. The tendency is to under estimate real axle weight. And, manufactures do not allow for all the add ons theirs or yours. It would be a shame to by a new rig and find out you are overloaded standing still. Then try going to the mountains with a non-aspirated gas engine that looses approximately 2% torque for every 1,000 feet of altitude. Pretty soon 45MPH over passes sounds good. You can't beat torque for pulling. That is why diesels are so popular in the RV business. Long ago the Suburban with a gas 454 cid was the best. I could make 25 mph over Raton pass on I-25. Now, with a big diesel, bigger trailer, I can drive the speed limit up hill and the grade brake keeps the speed at the limit going down hill. We have come a long way in RVing.
guskmg

[dkottum]

Yes, axle weight capacity plays second fiddle in most discussions about payload capacity. Doing the simple math, hitch weight plus truck load, and calling it good ignores the possibility of overloading of an axle, and ignores the function of the weight distribution hitch.

After setting up a towing combo, it's a good idea to weigh it at a truck scale. At least the first time. Our Ram 1500 has 3900 lb axles carrying near identical weights on each, it would be very easy to overload the rear axle and leave the front axle too light for good control. Loaded to GVWR we still have 850 lbs total axle capacity remaining, and plenty of tire capacity determined by tire pressure.

Modern gas engine/transmssions are quite capable and efficient compared to earlier engine/transmissions. We have towed our present Airstream over Raton pass both directions with a 4.7 Tundra and 5.7 Ram 1500 without problems. The 5.7 has excess capacity.

[FCStreamer]

I don't understand the distinction. Doesn't the payload number take into account the rear axel weight capacity?

I mean, my truck is not going to tell me it can have a 2000 lb payload if the axel can't handle it?

[dkottum]

Yes and no, you can load the truck to GVWR (actual truck weight plus load) and still be over an axle rating with a heavy trailer hitch weight. That one of the reasons weight distribution and scale weights matter.

For example our GVRW is 6950 lbs, our axle ratings (3900 plus 3900) total 7800 lbs. Hitching the trailer and truck bed load and us does not exceed GVWR, but without weight distribution applied it may overload the rear axle, the front axle load will be reduced.

[FCStreamer]

Originally Posted by dkottum

Yes and no, you can load the truck to GVWR (actual truck weight plus load) and still be over an axle rating with a heavy trailer hitch weight.

If I did that, I would most likely be over my payload number, wouldn't I?

[dkottum]

I think of payload number is a shopping tool, once it arrives at the dealer lot and they add any accessories (running boards, bed liner, mats, etc) the number has no accurate meaning. We buy the vehicle and add or remove anything, it becomes less accurate. We use GVWR, GAWR, GCWR (listed on the door sticker), and tire ratings at prescribed tire pressure to know our load capacities. The tire rating on the sidewall is at maximum pressure stated on the sidewall.

Every vehicle, load and hitch weight is different. I have not weighed ours without any w.d. applied. I do know w.d moves some of the hitch and bed load from the rear axle to the front axle, and some to the trailer axles. Our w.d. hitch has screw jacks to easily make adjustments, then go around and weigh again. (Interesting they or the scale wouldn't allow us to weigh again without pulling off and going around.)

By the numbers I see, I believe we may overload our rear axle without weight distribution. It doesn't matter because we would never tow without a w.d. hitch. Yours may be different depending on load, hitch weight, GVWR and individual axle ratings.

[MacPDX]

This is a review I wrote after a trip to Utah last year. I have an SOB that is similar in weight as yours.

---

We just returned from a 2300 mile trip, Portland, OR to Southern Utah and back. Figured I would do a review on how the Tundra tows.

Tundra is a 4WD TRD dual cab with the 5.7L iForce V8. Route was mainly interstates (I84 and I15) with state routes (Utah SR28, SR24, SR12, SR89, SR20) mixed in. Travel trailer weighed in at 6600 lbs wet. Tundra weighed in at 7050. With the trailer attached, the Tundra payload was exceeded by about 150 lbs. All other measures were within spec.

Speeds were kept between 59-62 MPH, except on grades as explained below. Gas mileage averaged from a low of 9.4 MPG to a high of 13.5 MPG per tank. Wind and elevation changes were the most common factor for differences. Overall, the average for the trip was between 10 and 11 MPG.

On level terrain, cruise control was set and the truck chugged along with minimal effort. There was some jostling/pogoing and one definitely "knew" the trailer was there, but there were no oscillation issues (uncontrolled sway) even in heavy winds or being passed by semis. The truck is softly sprung (TRD package) and has P rated tires; this probably accounted for the pogo effect. At no time did I feel unsafe.

The route contained many long steep ascents and descents. 8% grades were not uncommon and I saw as high as 10%.
The Tundra was also effective at pulling on hills. Except on the steepest grades, 50-55 MPH could be maintained easily, albeit with the tach north of 3500 RPM. On the steepest grades, 8%+, I would let off the pedal at 40-45 MPH to keep the RPMs within a comfortable range. No, not for the truck, because they are designed to run as high as 5000 RPM, but for my sanity because north of 3500 the sound is uncomfortable.

Downhill was another story. One really needed to get ahead of the curve and slow down to about 40-45 MPH prior to the descent. Otherwise, it felt like a runaway freight train and no amount of downshifting was going to reign it in without using some serious braking. Now, mind you, I am talking about 6%+ grades that were 1+ miles in length. One really doesn’t want to be riding the brakes for 2-3 miles. But, when I downshifted prior to starting the descent, I was able to maintain decent control, as long as I kept the speed slower than 45 MPH with a combination of braking and low gears. These moments were work and not all that pleasant.

The Tundra cruise control was probably the most disappointing aspect of the experience. The cruise control would inexplicably cut out on any serious grade. Cruise set on 60 MPH, truck begins ascent, truck downshifts, tach goes to 3500 RPMs, no problem right. Wrong. Even though the truck was marching up the hill, the tach bounced and the speed started dropping like an anvil off a cliff. Sometimes the speed would drop 20+ MPH before any sign of shifting. If I cancelled the CC, I could manually drive up the hill no problem. Disconcerting to the point I would take it out of cruise control when approaching any grade.

Downhill was even worse. CC set on 60 MPH cresting the hill, truck would start accelerating to 65-70 MPH before any hint of downshifting to control the speed. By this time it was too late for engine braking to be effective. The result was like a runaway freight train with me looking for the emergency ramps.

Thus, the cruise control was only effective on relatively flat terrain.

My conclusion is that the Tundra is a good match for trailers this size or smaller. I would not want to go bigger. And, if you only tow occasionally where there are steep grades, i.e. east of the Mississippi. If you are a weekend camper or travel within a few hundred miles from home, the Tundra makes a great TV.

[jcl]

Originally Posted by FCStreamer

I don't understand the distinction. Doesn't the payload number take into account the rear axel weight capacity?

I mean, my truck is not going to tell me it can have a 2000 lb payload if the axel can't handle it?

You need to think about where you are going to carry that payload.

Just for a moment, forget the trailer. In this example, you are going to put a 1000 lb cube of metal (similar in magnitude to tongue weight) in the back of your truck. If you put that 1000 lb cube somewhere between the truck axles, the two axles will each carry a portion of the load. All is good.

Now imagine that you are going to carry that 1000 lb cube right over the rear axle. The rear axle load will go up by 1000 lb, and the front axle won't change.

Now slide that 1000 lb cube back to where it rides on your tailgate (if you have one), positioned somewhere out behind the rear bumper. The axles are now not each seeing a similar share of the 1000 lb load. The rear axle is carrying more than 1000 lbs due to the effect of the lever applied by the 1000 lb cube. The front axle is carrying less than it was empty. The two still add up to 1000 lbs (imagine something like +1200 on the rear, -200 on the front, just using example numbers) but your rear axle loading matters now. You've gone from a portion of the 1000 lbs on the rear axle, to more than 1000 lbs, all with the same load.

None of the weights are real in this example, but the concept is. It matters where you carry the load.

Now swap the 1000 lb cube for your actual tongue weight (same relative position behind the bumper). Now apply weight distribution to (virtually) move the 1000 lbs forward, restoring front axle load. If you do so, your rear axle should be fine, but you won't know until you weigh it, loaded for travel.

The reason that the two axle ratings add up to more than the gross vehicle weight ratings is that the manufacturer doesn't know where you are going to carry the payload. They have to provide some margin when they design and rate the vehicle. You just don't know how much, and if it is all still good, until you weigh it.

Hope that helps.

Jeff

[SailorSam205]

Goodyear Tire Co has put together a really good guide that talks about GVWR, GCVWR, GAWR, etc. They also provide a recommendation on how to weigh your rig. As noted, you could overload one axle. Similarly, you could overload one wheel and still be under the rating for the axle. Take a look at: http://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf.

[CalifBob]

Is your Tundra a 4WD? If so and you have the factory towing kit - standard for most Toyota 4WDs with a hitch mount, you should have heavier brakes and a closed transmission with transmission radiator mounted in front of the radiator.

[PSU1981]

Yes - 4WD + tow package + hitch.

Not sure if it has transmission radiator?