Tire pressure conflict?

[Anniedog]

Book for my 88 Exella 1000 says tires at 55 psi. Cooper and Marathon say 65psi for my weight etc. Who is right? I noticed when I went from 55 UP to the suggested 65 with Marathons I cracked plastic headlliner in rear. Coincidence?
Love the trailer. Every now and then we wander through a fancy new 5th or a nice box trailer with slides etc. but always end up back in our "old" 29 footer.
Thanks folks.

[George Jr.]

I like to run mine at "max pressure" listed on tire sidewall.

[2airishuman]

hi anniedog and welcome to the forums

lots of threads here on tire pressures for both the t.v and the trailer. also on the load rating symbols (c,d,e) that various trailer tires carry. search a little and you can read your brain full...

what's the rating on your new tires?

my guess is that the tires made/spec'd in '88 may have had a max psi of 55. your new tires must be rated at 65......mine are too.

i agree the newest marathons will run the coolest and be most reliable at the 65psi cold inflation. that's also the pressure that supports their max load rating.

will that vibrate the trailer more? perhaps, but how much and to what degree is this a negative.......only inland andy can tell us for sure.......but he does say........

'safety first garrrrrrrr-un-teed!'

you could do some tinkering......first weigh your trailer/tv at a cat scale and get the axle load figures with full tanks and all your travelin' gear, and your hitch dialed in........if you are at max load for the tire (and not over the trailer max load), then go to 65psi and stop tinkerin'.....

if your fully loaded trailer is some fraction of max and you have a surface temperature sensor.....you could lower cold pressures some; travel 10-20 miles and re measure the temps......as you incrementally reduce tire pressures there will come a point that is tooo low and the tires will get warmer.....that would suggest it's time to re inflate a few psi.....

because properly inflated tires wear better, run cooler, support the load better, provide the best traction and help control/resist sway.........i'd suggest just going to 65psi and spend the extra effort rechecking regularly to make sure they are holding air properly.....

cheers
2air'

[bryanl]

First you should make sure your tires are properly rated for your trailer weight. Not too much nor too little. Don't get D rated tires when all you need is C, for instance.

After that, I agree with George. Inflate to the max pressure spec on the sidewall.

Low inflation is the number one source of tire failure. With modern tires, and especially for the low milage most trailer tires get, excess center wear from overinflation is not much of a concern.

The primary problem with tires that are more heavy duty than needed is that they tend to ride rough and that can hasten wear and tear problems in the trailer.

[Tinsel Loaf]

If you bought the correct tires for your trailer, follow the tire manufacturers specfications for inflation.

[axleman]

I guess that I would look at accountability, in the event of a failure.

Airstream will likely say - that's the tire manufacturer's responsibility. Sort of like Ford did with Firestone. Airstream makes trailers!

Just my two cents!

Regards,
Henry

[Anniedog]

Okay folks, I get the drift. Have always inflated to tire mfrs. reccommended for the load and check tire/hib temps regularly. Have blown a couple Marathons but switched to a set of Coopers and no trouble to date. It DOES seem to me our tire makers seem to be having a difficult time making tires that last. I am a NUT about proper inflation etc. and thus really annoyed when an apparently good Marathon blows. The worst part is not the #$%#$ tire....its what it does to my trailer!! HA!
Thanks again.

[overlander63]

Originally Posted by Anniedog

. Have blown a couple Marathons but switched to a set of Coopers and no trouble to date. It DOES seem to me our tire makers seem to be having a difficult time making tires that last. Thanks again.

I switched from Cooper Travel-Tracs to Marathons after a pair of Coopers bit the dust in a spectacular fashion on me. Like everything else, it is using what works best for you. I inflate my tires to the vehicle and trailer manufacturers' specifications, unless it is a Ford Explorer, but that is another story for another thread.

[uwe]

Here's a tire inflation chart from Good Year, for their RV tires. It references different tire pressures to max load ratings.

[Foiled Again]

Originally Posted by Leipper

...The primary problem with tires that are more heavy duty than needed is that they tend to ride rough and that can hasten wear and tear problems in the trailer.

I'm channelling "Inland Andy"... balance your wheel assemblies if you're experiencing rough ride... then you can inflate properly without rattling your trailer to pieces.

Andy... uh, ok Tin Lizzie

[JimGolden]

The important thing to remember is that underinflation is extremely dangerous. The tires overheat and the tread separates. From what I've read, that is what happened with the Ford Explorers and the Firestones. Ford had an inflation value stamped inside the door that was marginal. People would inflate to that marginal pressure, neglect to check the tire pressure for several months, and when they bled down five psi over time, they had an underinflated tire that heated up and separated. Car and Driver tried to replicate thse problems and with proper inflation, could not get a Firestone on an Explorer to blow at any speed. Only by underinflating them could they separate a tire.

All that being said, I think it's wise to trust the tire maker. However, if you really want to know for sure, get an infrared thermometer and try testing your tires. It may be that 55psi is just fine on your rig going 70mph on a 100 deg F day. Pump them to 55psi, take them out on the road for a half hour and get them warm and then quickly pull over and take a reading. Pump them up to 65psi and try the same test. That's how you really know for sure.

There's a large range between ideal, acceptable, and dangerous. You'd probably be OK at 55psi. Don't let them get to 25psi. The only way to really know is to actually test them like I mentioned above.

Good luck and let us know what you come up with.

JG

[wkerfoot]

Originally Posted by JimGolden

...
All that being said, I think it's wise to trust the tire maker. However, if you really want to know for sure, get an infrared thermometer and try testing your tires. It may be that 55psi is just fine on your rig going 70mph on a 100 deg F day. Pump them to 55psi, take them out on the road for a half hour and get them warm and then quickly pull over and take a reading. Pump them up to 65psi and try the same test. That's how you really know for sure.

There's a large range between ideal, acceptable, and dangerous. You'd probably be OK at 55psi. Don't let them get to 25psi. The only way to really know is to actually test them like I mentioned above.

Good luck and let us know what you come up with.

JG

Jim,


What temperature would you consider appropriate?

Bill

[Silvertwinkie]

I've had great success over the past 3 years and 2 Airstreams doing the 65psi cold with the Marathons. Heat isn't too bad either even in 90 degree ambient temps. I'd stick with what the tire manufact has listed, unless you in fact have the wrong tire for the coach.

[davidz71]

Originally Posted by wkerfoot

Jim,


What temperature would you consider appropriate?

Bill

Check the sidewall of all of your tires! It will have a max pressure listed. A C Range tire is usually 55 psi max. for a fully loaded trailer. Many run 55 psi no matter how the trailer is loaded to make sure that the tires are never running under inflated. As long as you are running 53-55 psi cold then you are fine but this would range from a lightly loaded trailer to a fully loaded trailer. I know there are charts out there that show what you can run "psi wise" for different loads. I don't trust the charts because I feel that an underinflated tire can cause you heat problems and failure down the road (no pun intended).

A D Range tire has a max of 65 psi so run your tires 63-65 psi. I can't advise running D Range tires at C Range pressures to limit shock to the coach because I found that probably lead to failure of one of my D Range tires.

[wkerfoot]

Originally Posted by davidz71

Check the sidewall of all of your tires! It will have a max pressure listed. A C Range tire is usually 55 psi max. for a fully loaded trailer. Many run 55 psi no matter how the trailer is loaded to make sure that the tires are never running under inflated. As long as you are running 53-55 psi cold then you are fine but this would range from a lightly loaded trailer to a fully loaded trailer. I know there are charts out there that show what you can run "psi wise" for different loads. I don't trust the charts because I feel that an underinflated tire can cause you heat problems and failure down the road (no pun intended).

A D Range tire has a max of 65 psi so run your tires 63-65 psi. I can't advise running D Range tires at C Range pressures to limit shock to the coach because I found that probably lead to failure of one of my D Range tires.

David,

I was after a temperature reading on properly inflated tires since Jim stated to measure the temperature of the tires at various inflation pressures. I run my tires at 35PSI as that is the recommended pressure on the manufacturer plate and each tire only carries 1450 lbs at the most.

Bill

[jimmickle]

I take an opposite stance on pressure. I got an accurate weight on my trailer when fully loaded and run pressure appropiate to the load. Once you get accurate weight, you can use the Goodyear chart referenced above to determine the minimum pressure that you should run. In the case of my 2002 25 ft Safari, with its ST225/75R15 Load Range D tires, 30 PSI would be sufficient to carry the load. If I didn’t have it loaded to GVW, I would even be OK at 25 PSI (40 PSI below recommended). To have some safety factor, I run my tires at 40 PSI (25 PSI under Airstream’s owners manual recommendations), which gives me excess capacity of about 300 pounds per tire. My tires run nice and cool, even on hot days. My trailer seems to ride smoothly, as nothing seems to jump around, even when we forget to take something off the counter or table before we get on the road.
Just because Airstream recommends higher pressure than is really required, or the tires have a higher maximum pressure, doesn’t mean you have to run the higher pressure and subject your trailer to higher levels of road shock. Overinflation reduces contact patch and subjects your unit to added shock. Go to Goodyear or Michelin's web sites to see what they say about proper inflation, get an accurate weight and inflate your tires properly.

[davidz71]

Originally Posted by wkerfoot

David,

I was after a temperature reading on properly inflated tires since Jim stated to measure the temperature of the tires at various inflation pressures. I run my tires at 35PSI as that is the recommended pressure on the manufacturer plate and each tire only carries 1450 lbs at the most.

Bill

Oops, my fault. It clearly says temp and I was thinking psi.

[davidz71]

Originally Posted by jimmickle

I take an opposite stance on pressure. I got an accurate weight on my trailer when fully loaded and run pressure appropiate to the load. Once you get accurate weight, you can use the Goodyear chart referenced above to determine the minimum pressure that you should run. In the case of my 2002 25 ft Safari, with its ST225/75R15 Load Range D tires, 30 PSI would be sufficient to carry the load. If I didn’t have it loaded to GVW, I would even be OK at 25 PSI (40 PSI below recommended). To have some safety factor, I run my tires at 40 PSI (25 PSI under Airstream’s owners manual recommendations), which gives me excess capacity of about 300 pounds per tire. My tires run nice and cool, even on hot days. My trailer seems to ride smoothly, as nothing seems to jump around, even when we forget to take something off the counter or table before we get on the road.
Just because Airstream recommends higher pressure than is really required, or the tires have a higher maximum pressure, doesn’t mean you have to run the higher pressure and subject your trailer to higher levels of road shock. Overinflation reduces contact patch and subjects your unit to added shock. Go to Goodyear or Michelin's web sites to see what they say about proper inflation, get an accurate weight and inflate your tires properly.

Jim,
I had the same stance until I had a blowout with a fairly new tire with low miles. I was running D Range and had them inflated to 55 psi. The 31' trailer was loaded to around 6,000 lbs. according to the local scales and I carried no water on board in any of the tanks.

[JimGolden]

Well I guess I opened the box here...

I'm not sure exactly what the temp should be. I'll have to check on this and get back to you. My buddy is an ASC Master Mechanic and has one of those infrared thermometers and he would have the details. My understanding is that your tires should never get so hot that you can't lay your hand on them, so I'd think you'd want them under 150 degrees F at least. I'm sure it's a function of the outside air temp too. I'd say in the summer time you'd probably want to keep them down to like 130 or so. There's probably a certain differential temp that is considered correct, like maybe 40 degrees warmer than the outside air temp. I'd think a tire company could tell us that.

Basically, if you run a higher pressure than necessary, the worst thing you'll do is grind the center tread off prematurely. It causes it to wear out quicker than normal, but it's not dangerous (although it will ride rough). Too low and they overheat and come apart. It's best to get it to the proper temp for your setup, but if you have to err, err on the side of overinflation.

If you can get one of those thermometers (they're not that expensive, I just haven't bought one myself yet...just bummed my buddy's), a good baseline would be to check the tire temp on your car. Whatever that comes up as, your trailer should be about the same.

I'll get hold of my buddy when he gets off Christmas vacation and see if I can bum his themometer and do some testing. He uses it a lot for figuring out the optimum tire pressure for his motorcycle. It's REAL bad if one of those tires comes apart. They're also handy for checking radiator temps, hose temps, the teapot on the stove. I really should get one

[gwsullivan]

According to the chart above, I can run tire pressures of 30 psi in my 25' Safari (gvwr 6300) and 60 psi on my 30' Limited (gvwr 9100). I have always inflated the tires on the Safari to 60-65 psi and noticed that things bounce around inside. When I tow the Limited with same tires and pressures nothing seems to move around inside. I think I will try running 35 psi on the Safari and see if it makes a difference. Any comments or concerns??