2021 Tow Capacity - Is it Safe

[Action]

Good year Marathon ST tires were not up for the job in many aspects. They were last manufactured in 2017. Goodyear redesigned their ST tire to a better (higher) standard into the Endurance tire.

The problem with the old Marathon tire is it could not handle higher loads very well. I forget how high a load it could handle but the Endurance exceeds that by a lot. And like many vehicles, trailers have gotten bigger and heavier. That growth needed a tire that could handle the load. Marathon was not that tire. The Endurance is far better in max load and max speed. Those pieces should have been manufactured into Marathon many years earlier. Goodyear was slow to make changes for a number of reasons.

The ST designation applies to light trailers with a GVWR of 10,000 pounds or less. And used to have a speed rating of 65 MPH. Which is the speed that the testing took place. Now ST tires can have as hig has a 87 MPH rating. The ST standards were set up specifically for trailers with non-drive and non-steering wheel. With stiffer sidewalls and typically a greater amount of chemical to resist UV.

Sounds like your bud was using Marathons and had a bad experience. He was not the only one. Especially with heavier trailers at freeway speeds. There just is not enough margin to handle uneven loading when at speed and the road isn;t that flat.

For my boat, I can move to a 15" rim. However by doing that, my 27' boat trailer has to go further down the ramp. And my TV would usually have to get wet or in some cases the exhaust and rear bumper goes under water. A 14" rim allows the boat to get into the water without backing the towed vehicle into the water. I know a 14" rim IS a limiting factor for tires as far as load. With a 14" rim diameter I have gone from four tires that has a max load rating of 7520 pounds to the Endurance that has a max load rating of 8800 pounds.

The previous tires fully inflated with a 7520 max load handling 7400 pounds is just not enough margin when freeway speeds are used.

I am not knocking LT tires. They will do the towing job just were not made for the towing job. So there are some minor down sides.

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[inmanlanier]

I am not knocking LT tires. They will do the towing job just were not made for the towing job. So there are some minor down sides.

Understood no disrespect, not taken. I've only had 1 LT give any grief - it was some separation showing. No failures and I've towed on them with limited margin to limit. My other bud in the tire business who turned me onto the LTs turned on a bunch of other clients as well (they raced cars like us and/or towed boats like me). He said in every instance his feedback was outstandingly positive. It's only the las few years the 'C' spec came out. I buy those for the same reason as you - margin. BTW - 5 more psi ove max is more margin - that's my other little secret.

 

[Action]

I tend to run higher PSI on all of my vehicles as a general rule.
The exception is my boat trailer. Those tires are maxed to PSI to get enough margin in load capacity.

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[inmanlanier]

Sorry - issues with webpage and tablet...

Are you sure you't not speaking of Goodyear Endurance as the decent trailer tire?

Our research shows data contra to your pressure claim - extra pressure in trailer tires will also help load rating.

More data on the 'C' spec here. https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=312

Otani (Thailand) are the 14" C tires I remembered - see Product – OTANI TIRE CO., LTD. select passenger, then after the download select light trucks and scroll down. There are 7 14" tires there.

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[Action]

That IS what I posted. Goodyear Endurance is a better ST tire than the pervious Marathons.
I have a set of 14" Endurance on my boat trailer. (215 75R14) Those have a D load range or 108N load index.

And what I stated is I max the pressure in my trailer tires to get the max rated load.

All of my other passenger vehicles the tire pressures are just a little bit higher than recommended by vehicle manufacturer. No where near max pressure on my cars and trucks. Just max pressure on the boat trailer tires.

The choice between Goodyear and Otani, is Goodyear has far more dealers nationwide. And I tend to use Discount Tire since they are headquartered in Arizona

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[inmanlanier]

Just to be clear, I tried to suggest that increasing trailer tires OVER the max by 5 psi is going to increase the tire's published load rating. Sorry if my published communique was confusing; I hate asynchronous communication since it is challenging much of the time.

I hope you have good results with the Endurance tires.

 

[Action]

Got it on the pressure

From another website (about Airstream trailers) there are two tire engineers that participate there.
What they have said is there is no increased in load capacity of the tire beyond the max pressure indicated on the side wall of the tire.

You can inflate (when cold) beyond the max pressure of the side wall of the tire however there is no added gain in load that the tire can handle.

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[inmanlanier]

Got it on the pressure

From another website (about Airstream trailers) there are two tire engineers that participate there.
What they have said is there is no increased in load capacity of the tire beyond the max pressure indicated on the side wall of the tire.

You can inflate (when cold) beyond the max pressure of the side wall of the tire however there is no added gain in load that the tire can handle.

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Very smart to have a rational basis from reputable sources.

I simply disagree with those two tire engineers based on research via my bud and specific dialog I've had with Yokohama tire engineers and more recently Michelin tire engineers. These dialogues were not related to trailer tires but were related to loads, pressures and speed. Even our 1969 Lincoln Continental owners manual said raise the pressures up 4 psi if cruising over 90 mph.

The faster the speed (and/or higher the load), the more severe is the curvature of the standing wave that develops where tread contacts the road (looking from the side at the road contact, it actually flexes up then back down in higher heights as speed/load increase). Said continuous belt flexure is what generates the heat that ultimately fails the belts/cord (essentially all materials lose strength as temperature increases). Greater pressure offsets the standing wave provide an opposing force, reducing the flex and reducing the attendant heat input. Yes, ultimately some amount of high pressure will fail the tire structurally - but that pressure is waaaay above the max rating.

I'll try and find some supporting info and PM you when I get home so you'll have basis for a potentially different perspective. I respect everyone's opinion. This one, however is dear to me because I've seen significant consequences from trailer tire failures. I just want to give everyone an opportunity to do all they can to avoid a significant financial hit due to something potentially avoidable.

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[Steedracer]

Great update! So...drove 6 hours in our (new to us) 2020 AWD Aviator with 202A/towing package, to go pick up a new boat (which is why we upgraded from a Volvo XC90 to the Avi). Okay, being very transparent here...so dry weight with boat and trailer, we are coming in at 6,750 lbs., which is 50 over capacity. Also, I had 2 to 3" too high hitch and ball, which added even more tongue weight/pressure to the hitch. As you can see in the first set of pictures (taken in a Meijer parking lot in IL), I was concerned. The Dynamic suspension hadn't raised and I was worried about the rear tires (remember the exploding Firestones on the Explorers in the early 2000's or so! Doh!). SO once underway,, the suspension leveled off. I watched the tire pressures like a hawk (i had overinflated to 40F/44R, and the trailer tires were at spec of 65 psi). I was very careful, giving everyone space and anticipating any stops of road obstacles. Bottom line, she towed like a champ, even with the tongue being a bit high, though I am glad there were no major hills on the trip. Going up, I averaged right at 25 mpg. Towing...11 mpg!...for 6 1/2 hrs. I kept my speed between 65 to 70mph mostly. Engine stayed around 2,500 rpms unless I was having to climb a bit. You can see the pics in my driveway, where the suspension has normalized and there is a 2 1/2 drop on the hitch. I should have towed it that way, but I was going off the boat's PO's pics with the trailer on his truck. Glad to have gotten the boat home. Moving forward, we will only be towing either from our storage area to the lake (about 4 miles), or to the dealer for maintenance (1 hr.). I'll attempt to attach the pics, through a Shutterfly link:
https://link.shutterfly.com/a9F5TSPH7rb

 

[ItzCurlyGirl]

I've wondered that for a while also.
As the original thread starter, just want to add that we have on order an F150 that will have margin when towing the size trailers we are looking at. We may sell or trade our Aviator as the dealers have offered us nearly what we paid. The truck is in production now and the "blend date" was 6/26. Hopefully only a couple more

 

[ItzCurlyGirl]

I've wondered that for a while also.
As the original thread starter, just want to add that we have on order an F150 that will have margin when towing the size trailers we are looking at. We may sell or trade our Aviator as the dealers have offered us nearly what we paid. The truck is in production now and the "blend date" was 6/26. Hopefully only a couple more months.

What did you decide? Are you wanting to still trade or sell your Aviator? What do you have? Might be interested if it’s what I’m looking for. Debating on finding a used or ordering new.

 

[peterk9]

What did you decide? Are you wanting to still trade or sell your Aviator? What do you have? Might be interested if it’s what I’m looking for. Debating on finding a used or ordering new.

Check the Signature on his post and it will show you some of what he has.

Peter

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[ufnavy06]

Bringing a nearly two year old topic back to life.

We didn't get the tow package on our GT (d'oh) and we're moving in a few weeks about 850 miles away.

I asked some questions in another thread about an aftermarket installed hitch but this thread is more about the towing capacity.

I'd be looking to tow the lighter of my two other cars (~3200 lbs) with a uhaul-style trailer (~2200 lbs). That comes in about 200 lbs less than the GT's capacity. Will I be OK if I decide to go that route with an aftermarket setup? Thanks!

 

[Action]

Generally, the tow package adds a trailer wiring, a hitch, bigger alternator, things that generally make it easier to start towing.
https://content.fordpro.com/content...df/towing-guides/2021_Lincoln_TowingGuide.pdf

Adding those later can work.
If it were me and I was towing more than one time, for distances greater than 50 miles, I would not exceed 90% of the tow capacity.

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[inmanlanier]

Not wanting to stir the pot here (like oil change intervals, brand of oil, etc.) I believe that the 'tow capacity' is not a well stated or understood parameter. There are many factors that would influence safety that IMHO you can't sum up into one value without context. A perfect example is an airplane where the takeoff weight limit changes with altitude based on the density of the air and density's impact on lift. Furthermore, once you take off of the runway you better shed alot of weight before you land or you'll fail the landing gear. One weight does NOT fit all circumstances.

The reality is that if your trailer has brakes, you can two a good bit more than the capacity at slow speeds (since your trailer will handle the big risk of rapid stopping). High speeds on the other hand impose different factors of risk (avoidance maneuverability, stability, etc.) and should be more carefully considered.

I have a 2012 Expedition that we chose to keep when we purchased the Aviator due to its higher tow capacity and our annual 5 hour trip to the Florida Keys. This trip we tow our boat where (depending on loading) it could approach 7000# in weight. Do we normally have that weight? No. But - since we are in summer conditions (high roadway temperatures) where the tire limits are taxed more, and we're doing 65 mph on interstates with looney toon drivers - I'm more cautious. To this very point, I now normally fuel the boat (150 gal capacity - 900# weight) down in the Keys where we're driving 45 to 50 mph and the higher weight is of lower risk. This way at the higher speeds I'm not as high a risk. For local trips, we use the Aviator - why? We never exceed 35 mph. Sometimes in the winter when I do a 45 minute tow to the county north of us for Spanish Mackerel - I'll use the Aviator since we're not at highway speeds for more than 20 minutes (and I typically will drop down to 60 mph for those trips).

Having said that - IMHO the limit can be utilized w/o concern. There is already margin built into the design. The engineers try and conservatively bound all conditions such that the worst case situation should be where the limit is. The higher the weight you tow - make sure you have good trailer brakes and that you've properly distributed the weight on the trailer so that it has some reasonable tongue weight and provides for a stable tow platform.

If you wish to curtail yourself at a lower threshold - you may - but I don't believe that it's necessary.

Please everyone respect our opportunity for differences of opinion. For what it's worth, I've been towing cars, boats and race cars approaching 50 years now. I've never had an event other than crappy trailer tires blow out (that's an entirely different tomb). I once had to make two severe and rapid towing evasions at about 45 mph and 65 mph due to lame brain passing me, pulling in front, then nailing the brakes. I'm a retired licensed Mechanical engineer with lots of experience turning wrenches including building a Factory Five Cobra.

 

[nauticman]

Bringing a nearly two year old topic back to life.

We didn't get the tow package on our GT (d'oh) and we're moving in a few weeks about 850 miles away.

I asked some questions in another thread about an aftermarket installed hitch but this thread is more about the towing capacity.

I'd be looking to tow the lighter of my two other cars (~3200 lbs) with a uhaul-style trailer (~2200 lbs). That comes in about 200 lbs less than the GT's capacity. Will I be OK if I decide to go that route with an aftermarket setup? Thanks!

Towed a 51 Ford truck on a U-Haul car hauler with my 21 aviator grand touring with tow package and air suspension. I was very concerned since I didn't know the trucks weight with a larger swapped engine, plus the GTs lower towing capacity. Hitch said 6,600. I now know the truck was ~3300 so I was ~5500. With the extra power of the GT the ~300 miles was effortless averaged 14mph. No issues stopping or climbing hills. Mirrors would be my only complaint vs my old ('18) navigator.

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[peterk9]

Towed a 51 Ford truck on a U-Haul car hauler with my 21 aviator grand touring with tow package and air suspension. I was very concerned since I didn't know the trucks weight with a larger swapped engine, plus the GTs lower towing capacity. Hitch said 6,600. I now know the truck was ~3300 so I was ~5500. With the extra power of the GT the ~300 miles was effortless averaged 14mph. No issues stopping or climbing hills. Mirrors would be my only complaint vs my old ('18) navigator.

Welcome to the Forum.

Peter

 

[inmanlanier]

I have moved away from rubber valve stems and only use metal valve stems on trailers no matter what tire pressures used. The tire shop will specify rubber for the trailer because the pressures are low compared to some other vehicles. Just eliminating past problems.

Action

View attachment 14294

Thinking of you yesterday, Action towing back from the Florida Keys. One of my 3 year old combo tire valve stems (base rubber, then brass, then rubber top) failed at the large bulbous base where it goes through the wheel opening. Thank goodness I had a wifi sensor on each tire and saw it leaking before catastrophic tire failure. Naturally the alarm went off on the 7 mile bridge!!! We were down from 67 psi to 37 psi by the time I got off the bridge to a safe spot where I could change the tire.

I just ordered some like your picture but brass (I use my trailer in Salt Water). Hopefully those will last longer.

What a pain with POS MIC SH$T these days! They have no clue how to mix polymers/rubbers.