Questions for those towing travel trailers with 2016+ LX570 (1 Viewer)

TeCKis300

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This is all wonderful info, thank you! A few follow-ups:
  1. The tongue weight of 800lbs seems over the factory recommended 700lbs, were you able to weigh your whole set up? Maybe a broader question, where does one go to get their total GCWR?
  2. How accurate is the TPMS to manually checking the tires? The manual recommends 39psi for the rear tires when towing and 33psi for the front, did you inflate all 4 tires or just the rear?
  3. 80 gallons of water is 667lbs, wow! At an RV park, do they have fresh water hookups on each site or do you fill-up at a central location prior to parking? Great tip to avoid weight especially if water is available at the camp site.

1) From the manual for the 2020 LX570. These numbers have changed over the years, with significant changes when SAE J2807 was applied. I wouldn't sweat +/- 100lbs, and a properly adjusted WD hitch will distribute weight to the forward axle, and back to the trailers axle.
1620072025987.png


2) Don't worry too much about precision or accuracy with tire air pressures. They change and fluctuate anyways with atmospheric conditions, and there's margin, so it's futile to geek out here. If towing at the upper ends of the spectrum, it's reasonable and can be beneficial to go above those pressures by 3-5 PSI, particularly in the rear axle.

3) I always travel with full fresh water tanks, though full tanks in my Airstream is 40 gallons. My laden trailer is almost 8k and 1200lb tongue. I tend to boondock or camp without hookups, and an RV doesn't make a great home without water. Water is usually the constraining resource.
 
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This is all wonderful info, thank you! A few follow-ups:
  1. The tongue weight of 800lbs seems over the factory recommended 700lbs, were you able to weigh your whole set up? Maybe a broader question, where does one go to get their total GCWR?
  2. How accurate is the TPMS to manually checking the tires? The manual recommends 39psi for the rear tires when towing and 33psi for the front, did you inflate all 4 tires or just the rear?
  3. 80 gallons of water is 667lbs, wow! At an RV park, do they have fresh water hookups on each site or do you fill-up at a central location prior to parking? Great tip to avoid weight especially if water is available at the camp site.
My trailer is full of stuff given the variety of things we do, limited access to support where we camp, and weather we can experience camping. Most of the time I’m pushing the 6800lb GVW limit without full water tanks.

I typically travel with 1/3 fresh water tank and the grey and black tanks empty. If I wasn’t carrying so much weight of stuff I would carry more water. When I head north or east of Fairbanks though it’s always with full fresh water. Tundra water is nasty... :notworthy: further north you go the worse it gets.
 
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Yes, I would encourage more RPM. Max HP is @ 5600rpm for the 5.7L. Not to necessarily shoot for that as a target unless you need max oomph, as it's also its own relative peak stress level, but there is lots of room to operate with higher RPMs.

The idea with rpm is to use more combustion events to help do the climbing work. Rather than big heavy combustion events at max torque, apply more lighter combustion events. RPM also helps with additional coolant and oil flow, both in the engine and transmission.

The 5.7L is overall a strong and flexible motor. It's likely happy to operate low, high, and everything in between, so it's really just an optimization recommendation.

Perhaps also interesting is the climbing performance available at max HP. HP is ~200HP @ 3500 RPM vs ~320 HP @ 5600 RPM.

View attachment 2664034
That's what I did in practice. On the high altitude, steep grade, I was between 2nd and 3rd gears. 2nd gears had me around 5k RPM and the car was willing to still pull. Didn't sound great, but I know I had Toyota reliability. When on 3rd gear, I was down to a more reasonable RPM around 4k RPM. But the car was struggling to hold speed on the uphill and I didn't want to lug the engine.
 
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This is all wonderful info, thank you! A few follow-ups:
  1. The tongue weight of 800lbs seems over the factory recommended 700lbs, were you able to weigh your whole set up? Maybe a broader question, where does one go to get their total GCWR?
  2. How accurate is the TPMS to manually checking the tires? The manual recommends 39psi for the rear tires when towing and 33psi for the front, did you inflate all 4 tires or just the rear?
  3. 80 gallons of water is 667lbs, wow! At an RV park, do they have fresh water hookups on each site or do you fill-up at a central location prior to parking? Great tip to avoid weight especially if water is available at the camp site.
You're welcome.

- I was unable to find a scale. I used some back of napkin calculations to arrive at that estimate. But I may have been off +/- 50 lbs. I also didn't realize that some truck scales on the interstates are available when the signs say closed. Good to know for next time.
- TPMS in the vehicle doesn't account for altitude variance. Since I was at high elevation, the dash gauges likely read 3 to 4 lbs higher than actual. That said, I was closely observing how much higher the PSI went from cold to when on the highway. It must have raised good 6 to 7 lbs, which was borderline of what I was comfortable with. The additional weight can cause the tire to overheat. Ironically in some cases and counterintutitive, you want to add more air to a tire if the PSIs are reading high due to overheating. The 21" rims on the LX only have Dunlop or Yokohama P rated tires in that size. I was aware that this could have been a potential troubleshoot before towing, so I kept my eyes on tire pressure during the trip.
- The owner of the trailer had topped off the water tanks as a courtesy. If it were up to me, I would have only carried 10 to 15 gals, as the site we went to had full hookups. I felt bad dumping all the water they had just filled prior to my pickup. So I left with the extra ballast:p
 
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You're welcome.

- I was unable to find a scale. I used some back of napkin calculations to arrive at that estimate. But I may have been off +/- 50 lbs. I also didn't realize that some truck scales on the interstates are available when the signs say closed. Good to know for next time.
- TPMS in the vehicle doesn't account for altitude variance. Since I was at high elevation, the dash gauges likely read 3 to 4 lbs higher than actual. That said, I was closely observing how much higher the PSI went from cold to when on the highway. It must have raised good 6 to 7 lbs, which was borderline of what I was comfortable with. The additional weight can cause the tire to overheat. Ironically in some cases and counterintutitive, you want to add more air to a tire if the PSIs are reading high due to overheating. The 21" rims on the LX only have Dunlop or Yokohama P rated tires in that size. I was aware that this could have been a potential troubleshoot before towing, so I kept my eyes on tire pressure during the trip.
- The owner of the trailer had topped off the water tanks as a courtesy. If it were up to me, I would have only carried 10 to 15 gals, as the site we went to had full hookups. I felt bad dumping all the water they had just filled prior to my pickup. So I left with the extra ballast:p
Also given that I didn't have a WD hitch and fully knowing that the tongue rate was on the rear axle, I only added air to the rear tires.
 

stonekutters

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Thank you @Kieranz @coleAK @TeCKis300 and @Dan Higgins

Some good takeaways:
  • Loading up on water makes sense if going to a remote location or where water quality is unknown / poor.
  • If going to a RV campground its less weight to tow and better to fill-up on the camp site.
  • Keeping RPM high but below peak torque for climbing.
  • Research on trailing specific forums / YouTube channels for more info.
  • Weigh stations are a good option to weigh the TV + TT even if they are closed.
  • Tongue weight of +/- 100lbs is ok as long a good WD hitch is used.
 
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All this talk of hauling water reminded me of the one thing that makes rving different from all other towing. When you stay at a place with a sani dump don’t leave without emptying the tanks. There’s just no reason to haul used food for no reason but there’s lots of reasons to dump it.
 

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