Tow Vehicle rear tire inflation while towing?

[routlaw]

Thus far I've never changed my tire inflation while towing any of our campers in the past, but having just installed a new set of tires on our '13 F150 EB got me to thinking should the rear tires be over inflated from the manufacturers recommendation provided on the door jamb stick while towing? Interestingly I contacted both Ford customer service as well as Michelin customer service and neither company would provide an answer. Spent some time researching this on the net and as you might guess "expert" opinions are all over the place, some being quite dogmatic. Shocking right?

 

So I thought I would throw this out there for an informed discussion.

 

Thanks

 

 

 

 

[STEVEnBETTY]

Increasing tire pressure will decrease rolling resistance, lower operating temperature,and increase fuel mileage, up to a point.

[bugeyedriver]

Check your vehicle's owner's manual under TOWING and see if it says anything about that.  My '84 Nissan pickup's manual actually said to increase the rear tire pressure when under load.  It helped to keep the truck level because the tires did not squat as the sidewalls puffed out. Although that little truck is history, I still follow that practice when I am towing.  While doing all the things STEVEnBETTY mentioned, it will also help reduce wear on the rear tires because they will not flex as much.

 

Be sure not to exceed the pressure limits found on the sidewalls of the tires.

[Try2Relax]

That would come down to what the specifics of your tire are and what your numbers are from a proper weighing, while fully set up for towing.

 

Maximum weight carrying ability and sidewall strength is achieved at maximum tire inflation, as indicated on the sidewall of the tire. From there each manufacturer has charts explaining what different pressures achieve in regards to weight carrying ability.

 

For example LINK

[STEVEnBETTY]

Just remember to return to normal pressure when unloaded, it will increase wear on the center of the tire because it reduces the area of the tire that actually contacts the road.

[KarenLukens]

Check your vehicle’s owner’s manual under TOWING and see if it says anything about that. My ’84 Nissan pickup’s manual actually said to increase the rear tire pressure when under load. It helped to keep the truck level because the tires did not squat as the sidewalls puffed out. Although that little truck is history, I still follow that practice when I am towing. While doing all the things STEVEnBETTY mentioned, it will also help reduce wear on the rear tires because they will not flex as much. Be sure not to exceed the pressure limits found on the sidewalls of the tires.

 

+1 on a lot of the answers. But you said over inflate past the max recommendation on the door of the car? I don't think that there's a reason to go past max inflation. On our door it gives me 41lbs for normal and then to inflate the tires up to 48lbs when towing. If you don't add air and you're towing a lot, then the tires will wear out on the outside edges. I'm always watching the treads on our tires and today I took it up to the 48lbs that they recommend just to see where it rides being that we are towing constantly right now. With the Casita, 4lbs extra worked fine and I'm thinking that I will end up around 6lbs over with the Elite II, which is still under the 48lbs max on our car. Still though, watching the tires is the best way to tell.

[routlaw]

Thanks for all the info, just a quick followup. Have checked several times with my owners manual regarding tire inflation for towing, zero zilch nada in the Ford manual, go figure, but just went through all of my manuals once again just in case I missed something. Again nothing. Thus the phone calls to the Ford and Michelin.

 

Allow me to clarify a few things. My terminology might not have been correct on inflation. On our F150 the door panel says 35 PSI with a Max of 44 PSI but no info regarding loads, towing and what those values should change to from pound by pound. So by over inflating I meant going past the normal 35 PSI, certainly not 44. I should also add while towing with the standard recommended PSI the truck and camper handle just fine and I have not noticed any unusual wear between the center and outside with the older set of tires, though curiously one tire did have more tread life left and like most of you I check tire pressure often especially before heading out on a trip.

 

The new set of tires, are a bit unusual in that they are NOT a true LT tire, but also are not categorized at P rated tire either and the load rating has been notched up from a 114R to a 116T allowing for something like 2756 lbs of load. So one wouldn't think 450-500 lbs at the hitch would not be much of an event, but it seems like the consensus is everyone else is deriving better performance from higher inflation above the standard recommended. For this upcoming trip based upon the suggestions here I think I will bump up the PSI to around 40 on the rear tires and see how that goes.

 

Thanks

[Try2Relax]

Just as a side note, if you happen upon a scale, stop by. I don't know if your using an Andersen, I'm guessing you are with an F150 as the hitch requires it I believe, anyways you will probably find that your front axle and rear axle are about the same weight, as such when loaded with a trailer on the back and an engine up front you'd probably be better served raising all of them up to 40psi.

 

Oh, if they don't have "LT" printed on them, then they are in fact "P" no way around it (and LTX doesn't count, they're "P")

 

What size are yours?

[bugeyedriver]

Reed & Karen,

 

Spot on!  Watching the tires is the best measure of proper inflation.  After driving over a dusty surface, look to see if the dust covers the tire from one edge of the tread to the other edge.  This would be and indication of proper inflation.  If there is a space from the dust on the tire to the edge of the tread, you are over inflated and may experience faster wear on the center of the tire over time.  Dust extending past the tread and onto the sidewall would indicate under inflation and the tire will experience excessive flexing, potentially leading to sidewall failure over time.

 

As far as the door numbers go, my Tacoma recommends 29 psi on all four tires.  That gives a real nice, smooth ride and handling and sells a lot of Tacos.  My Micheline LTX 10 ply, load range E tires can handle 44 psi cold tire pressure.  I've also added a Roadmaster Active Suspension to my truck which greatly aids with load bearing duties.  When I head out, fully loaded for extended camping, I use 35 psi in the front and 42 in the rear.  That is over the door number recommendations, but for hauling and towing, it works fine, keeps the rig level, without exceeding limits on my tires.

 

Monitoring their pressure and temperature with a TPMS system is also part of my scheme.

 

Pete

[routlaw]

Nope, never used an Andersen and don't intend to because it doesn't seem necessary based upon 10,000 miles of pulling the Oliver so far. And much of this has been in some extreme conditions. The hitch only requires it on my model once you get over 500 lbs, so granted we are on the cusp of being road illegal. It wasn't until I brought this subject up with the Oliver Company both here on this forum as well as the FG RV forum a couple of years or so ago that they even offered to install a WDH. As we were waiting on delivery of ours I stumbled upon information requiring WDH's otherwise tow and tongue weights were cut in half ± a few pounds. I would venture to guess the majority of people towing regardless of the load and type still are not aware of this. But from what I understand this is still not a law implemented by the DOT, rather an effort for the industry to create some sort of standard.

 

You might be correct about the "P" rating but I find it odd that in every other case Michelin does rate their tires as "P" when applicable except for this one which does have some notched up specs. They are the Defender LTX 275/65R/18's

[routlaw]

Pete I have also been looking at that Roadmaster Active Suspension for the last year or so too. It makes a lot of sense. Sounds like you are pleased with the performance then.

 

Interesting observation system with the dirt road scenario too.

[bugeyedriver]

The Roadmaster system is awesome while unloaded or while towing for my Tacoma.  I couldn't be more pleased.  Go for it!  It also has a minor effect on increasing gas mileage a bit because it greatly reduces the sidewall flexing and thereby reduces the tire footprint on the road (due to flex) and reduces rolling friction.

[Try2Relax]

Found what I was looking for, attached.

 

Oh - Load Range E tires will have an 80psi max pressure stamped on them.

tmp_32031-DiscountTireinflation-1075504931.pdf

[routlaw]

I remember seeing that video regarding increased gas mileage for exactly what you're describing, sound like it might not be hype.

 

Interesting tire chart you found there Randy. But when I went to the C load range the chart returned a 50 PSI result for my tires. Thats a bit more than I'm comfortable with for now.

[routlaw]

Never mind that last note about C range, my bad