safe tire pressure, advice anyone?

[FrankA]

Hey folks-

Need some advice on safe tire pressure while towing about 9,000 lbs. on hot road surfaces over mountains here out West. Inside the front driver's door says 70 lbs. rear and 60 lbs. front but that's probably w/out weight. The max. tire pressure stated on the tire itself states 80lbs. I have the Michelins LT265/R70 series that came stock with the truck ('07;68RFE;auto). What do you think?

thanks-

frank

 

[mberry]

That depends on the hitch weight. If I were you, I would run 65 all around and not worry about it. I've towed that weight and more at 65lbs in the tires at temps over 100 and the tires were barely warmer than ambient temp.

Right now I'm running 75 front and rear and towing an 11K 5th wheel with around 1350 pin weight if that helps you. No tire issues ever on two Dodge Ram trucks for me, except wearing them out too fast.

Where exactly out West are you referring to?

Someone will chime in here with different opinions/advice I'm sure. Hope this helps.

 

[KFranco]

My door says 65 front and 80 rear. "E" rated tires I have allow you to fill up to 80psi. I fill them up to these specs because the more psi will create less rolling resistance or flex on the sidewalls as you increase the weight on the tires. Flex on the sidewalls acts like mini-hills and more work is required to overcome this. (for example: steel wheels on trains provide very little rolling resistance which is needed for all the weight they carry)

 

[gjones813]

When towing I max mine out to 80lbs, My semi says 110lbs and that what I put in them no exceptions. you don't want flexing sidewalls. If you have to take evasive actions you don't run the risk of seperating the tire from the rim.

 

[WestTN]

The door post numbers are the minimum requirement for a truck loaded to the maximum factory axle recommmendations. If you are loaded differently from those spec's then you need to adjust accordingly. And you can air up for better fuel economy. I have gone as far as 85 psi for better fuel economy and tire life.



ISO tire standarda allow huge inflation pressures in specific situations.

 

[SSell]

I'd have to look to be positive, but my 05 SRW 3500 has a "supplemental tire info" sticker---says for heavy load 60 front, 75 rear... . used this on E rated 265 & 285 tires with good results in arizona (about as hot as you're gona get). Bought an infrared/laser thermometer thingy that I check tires with whenever I stop---usually find back tires run 10-15 degrees hotter than fronts, side to side usually the same with my Equalizer hitch cranked up sort of tight (with my 10K toyhauler rear sags about 2", front lift about 1/2" from empty state). When in doubt, air up to max on tire sidewall, watch for any single tire getting hotter than it's axle-mate, keep it down to 65mph (baby the trailer tires but beware the overloaded rear truck tire) Oh yeah, upgrade your airstems if get the chance, had 3 rubber ones fail on me, never had a metal one come apart yet.



my . 02 and then some

 

[Jim W]

These are all great replies that you have received from everyone.

I believe in your sig you list a 2007. 5 (6. 7L) truck, correct? If this is correct and you have TPMS installed, these pressure that are recommend by everyone may trip your warning system.

I tow a 5er also with a 1700 pin weight and I run my tires at 70 PSI front/rear. I use a heat gun and check the tire temps when I stop at various rest areas. My rear tire temps have been in the low 100's with an ambient temp of 70F+. In fact my RF tire was always hotter then the rear tires by 5 degrees. Checking your tire temps are the best way to check for tire issues when towing. On another forum one user provided a chart for tire temps at various ambient temps with his tires never exceeding 140F+.

Just my $0. 02

 

[THoltz]

The Michelin tire manual that came with my truck said for full load run 65 in front and 50 in the rear tires for my dually. My point is maybe you should refer to your tire manual if you have one or ask Michelin.

 

[Skydiver]

85 psi front, E-rated 8-ply goodyears



28-65 psi rear (dually), E-rated 10-ply Goodyear G-90s



On the rear there is a little as 640 lbs on each tire when unloaded. That is why and when I run 28 psi. Makes them wear even.

The biggest problem I see is people running 4-ply tires on diesel pick-ups. With at least2275 lbs on each front tire, running a 4-ply is asking for trouble.

I read that on an extended cab long bed the weight different front to rear is 65/35%.

 

[MAllen1]

I would run according to what is on the tire, not the door. I always say that if the auto maker had any authority on what tire pressure to put in the tire, they'd be in the tire business (Remember the Ford/Firestone problem. I was a mechanic for Ford at the time. Firestone stated putting 40 psi in their tires. The door jab of the Exploders said to put 26 psi. HHHMMM!).

 

[SMorneau]

All tires of a given size are supposed to be designed to a basic set of standards. You can download a load inflation guide from the Goodyear site that will tell you how much pressure to put in a given size tire, at a given load, in either a SW or DRW configuration. This chart really works you just have to know the axle weight of your rig. I have used it for years on different makes of tires and it saves a lot of trial and error. That said, when I have the camper on I max the air pressure out.

 

[MMeier]

KISS... . run them at the max on the sidewall... . 80 PSI Cold.

 

[macdaddy]

Any SRW truck loaded to/at its rated GVWR should go by the tire.



Id run 80 psi cold... ...



Mac

 

[AABEN]

When towing I max mine out to 80lbs, My semi says 110lbs and that what I put in them no exceptions. you don't want flexing sidewalls. If you have to take evasive actions you don't run the risk of seperating the tire from the rim.

I will go alone with you. I did the same when driving the big rigs and do my dodge and fifth wheel the same.

 

[Grizzly]

Hey folks-

Need some advice on safe tire pressure while towing about 9,000 lbs. on hot road surfaces over mountains here out West. Inside the front driver's door says 70 lbs. rear and 60 lbs. front but that's probably w/out weight. The max. tire pressure stated on the tire itself states 80lbs. I have the Michelins LT265/R70 series that came stock with the truck ('07;68RFE;auto). What do you think?

thanks-

frank

First off you should include your signature so that we know if you have a SRW or a DRW. Then include the trailer, is it a 5er or a pull behind TT. You need to know your pin or hitch weight. If you don't know, get the truck and trailer to a scale. Calculate your pin or hitch weight.



Where out West are you towing, Calif, Washington, Arizona, Colorado, New Mexico or Nevada? That's very important to determine elevation of mountain passes and ambient heat of highway.



To say 55 psi all around or 80 psi all around isn't good enough. You need to know what your load is and what the terrain is.

 

[Loren]

While you probably can't go wrong using either the pressures listed on your door or the maximum pressure from the tire sidewall, I would pump them up to the maximum.



Have you EVER heard of a tire failing because the driver was running a tire pressure that was too high?



I haven't either.



Good luck.

 

[THoltz]

I am a little nervous about running at the max side wall pressure. I like to have a little margin between actual and maximum pressure.

 

[Loren]

I am a little nervous about running at the max side wall pressure. I like to have a little margin between actual and maximum pressure.

THoltz,



You are free to use whatever tire pressure you feel comfortable with. Here are my thoughts:



1. While studying engineering, I realized that products are designed for certain specifications plus an additional margin for safety. I never learned anything about tire design, but I would guess that for something that critical, the safety margin is large.



2. The ONLY time I ever learned of a tire failure from overpressure was when I was still in high school. I was working for the summer in a construction crew at a service station. The station was still open, and a young boy brought his bicycle for air. He didn't have a tire gauge, and may not have even known how to use one. He started airing his tire with the 175 psi air available at the island, and eventually I heard a "POP". He had popped his inner tube with the high pressure air. I only assume that he also popped the tire, but I didn't check. The last I saw of him he was crying and being taken inside the station by the owner to see about patching his tire.



I have NEVER heard or read about any automotive tire failure from too much pressure. I have heard and read about many failures from too little pressure.



You pay your money, and you take your choice.

 

[AABEN]

Well a low tire will get hot if you have it to low. Why do you thank dodge or the tire maker puts the air presser on there truck or the tire maker does it!! Look what FORD did with the light air pressure !!!