Recommended Tire Pressure for Towing TT RV

[madsend81]

Having read a lot of threads and recommendations on towing, increasing tire pressure on the tractor vehicle seems to be a common suggestion to improve handling and mileage. I'm towing a 4,000 lb, 21' Jayco from San Diego to Tucson on Wednesday with my Powerboost. It will be our first trip towing an RV trailer. Tires on my PB are Hankook Dynapro AT2, size 275/60R20's. Door sticker says 35 psi, but I know that's for regular driving.

What pressure does everyone here recommend for my situation? Serious recommendations appreciated.

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[redline]

max pressure that the tire allows

 

[Buyer2021]

Door sticker says 35 psi, but I know that's for regular driving.

The door sticker tire pressure is the minimum recommended pressure for the spec tires loaded at the rated GAWR not exceeding the GVWR.

What is the actual weight on the truck tires (axles) with your rig ready-for-travel? The important thing to know is not your trailer weight but the load on your truck's tires (axles) with the trailer hitched (you don't mention whether you use a WDH which will affect actual truck tire (axle) loading) and everything loaded for travel including people and cargo in the truck.

If you don't know, hit a CAT Scale along the way on your trip, topping-up your gas tank and taking care to ensure that your truck front tires are on one platform, your truck rear tires on another, and all trailer tires are on a third platform. Note this may require that you not pull all the way forward to the 'big-rig' line on the scales. The cost for a single weigh is ~$13 dollars, money well-spent for the information gained.

My personal experience:

• My truck has a GVWR = 7050#; Front GAWR = 3450#; Rear GAWR = 3800#
• The sticker tire pressure is 35psi Front and Rear for my 275/65R18 tires
• The sidwall max tire pressure is 51psi for 2756# max load
• When my 3950# actual weight 5th wheel with an actual pin weight of 780# is hitched to my truck loaded for travel with a full 36-gallon fuel tank, the actual truck CAT Scale weights are
• Front axle = 3200# (1600#/tire)
• Rear axle = 3200# (1600#/tire)
• Total weight of the truck = 6400#
• Note all the actual weights are well-below the respective gross and axle weight ratings and less than 60% of the max tire load rating

I find my sticker 35psi cold tire pressures give good handling and performance when towing my rig; I've experimented bumping them up +5psi cold and all I got to show for that was a harsher ride (didn't run that long enough to judge tire wear effects).

IF you feel the urge to bump-up your truck tire pressures, based on the rig you describe I'd run for a day on the cold sticker pressure then the next morning go +5psi cold and see how that feels. Adjust / tweak from there.

IF your load were pushing the limits of your truck's GVWR / GAWRs, I might suggest different. But in no case would I recommend jumping to the max pressure on the tire sidewall ...

max pressure that the tire allows

Max pressure that the tire allows is to support the max load that the tire allows. With OE tires this will doubtless be well-above the vehicle's GAWR's & GVWR.

The Hankook specs for the OP's tires doesn't list the max pressure, but it does list the max load as 2679 pounds. That'd be 2 x 2679 = 5358# per axle or 4*2679 = 10,716 Gross Vehicle Weight. That's probably well over the actual load the tires will carry on the OP's rig. An unnecessarily harsh ride and poor / uneven tire wear will likely be the result, IMO.

BTW, this being your first real trip with your RV, don't be too quick to attribute the different 'feel' when towing to your tire pressures as long as they are at least at the sticker value for both the truck and trailer. You're going to be experiencing a different 'feel' for the first time just by virtue of towing long-distance for the first time - it'll take a bit of acclimatization. You and your rig will be safe if you just stick with the sticker tire pressures until you get more comfortable with the towing experience.

IF you happen to sense a feeling of trailer sway, that's likely NOT a tire pressure issue, it's a telltale of too-little tongue weight; move weight in the trailer toward the front (or move cargo from the truck to the front of the trailer) and readjust your WDH for level ride accordingly.

All just for your consideration, Relax, Have Fun, enjoy your trip!

 

[Hullguy]

My friends at the local tire shop dont recommend increasing the psi in the tow vehicle tires while towing. This is because the tire pressure will increase due to heat from the road and friction

 

[Samson16]

I have the same tires on my Powerboost and even unloaded the handling tightens up at 40psi cold. I think the max is 51psi so well within operating specs. With the additional 400-600lb. of tongue weight that’s where I would start. Easier to remove air if the ride is too harsh (It won’t be) than to add air later.

 

[madsend81]

Thanks for the responses. For the record, I will be using a WDH with sway control.
I know the PB can handle the load. Just want to make sure I'm maximizing the performance without overthinking things.

 

[madsend81]

Just finished the first leg of the trip from San Diego to Yuma, just under 3 hours, 115 miles, 4,180ft elevation change with headwinds. Averaged 10 mpg. Used 1/2 tank of gas. Truck managed it all at 62 mph without the engine or transmission temp gauges moving a bit. Trailer handled well going up and down the mountains. Ride is nice and smooth. Wife and my 6' tall boys are appreciating the extra room of the SuperCrew cab. 4 yr old daughter is hanging in there like a champ. ~4 more hours to Tucson.

 

[madsend81]

2nd leg of the trip is done. Took 4 hours from Yuma to Tucson due to making a couple extra stops for potty breaks. Headwinds were pretty strong. Tried drafting behind some tractor-trailers to improve gas mileage. Overall trip mileage was 10 mpg. Never felt like the truck didn't have the power if I wanted to let it. It's like I was holding it back to improve the mileage.

 

[Buyer2021]

just curious - what cold pressure did you run?

 

[madsend81]

After the comments, I elected to try it at 35psi since the trailer isn't that heavy. Tires don't look like they are suffering. Pressure only rose 1 psi when they warmed up.

 

[Ed21]

Simple answer 35 psi as per door sticker. 5800# TT as per cat scale, both axles under gvwr. 5000 miles of towing. No abnormal tire ware. No handling problems and 9-10 mpg. cruising no faster than 65 mph. I’m satisfied.

 

[Ed21]

Ha ha, I meant tire wear!

 

[madsend81]

Ha ha, I meant tire wear!

I knew what you meant, even if it was spelled wrong.

It does make you wonder what tire ware might look like!

 

[SRMD]

Just finished the first leg of the trip from San Diego to Yuma, just under 3 hours, 115 miles, 4,180ft elevation change with headwinds. Averaged 10 mpg. Used 1/2 tank of gas. Truck managed it all at 62 mph without the engine or transmission temp gauges moving a bit. Trailer handled well going up and down the mountains. Ride is nice and smooth. Wife and my 6' tall boys are appreciating the extra room of the SuperCrew cab. 4 yr old daughter is hanging in there like a champ. ~4 more hours to Tucson.

Just so you know, the idiot gauges typically do not move, even though your transmission and coolant temps are rising, quickly. I have had my engine coolant close to 240F and idiot gauge was still dead center - the same place it sits when coolant is at 195-200. This is the same with the transmission.

Do yourself a favor and get an Mx+ or something similar, use TurboPilots 1.4 or 1.5 version of PIDS to monitor your real transmission and coolant temps. If towing into headwind with TT, they will be higher than you think. Stay in 7th gear to manage the boost to keep temps under control.

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