Tire pressure?

[Minnie's Mate]

Does anybody know how hot is too hot for the tire temperature? While I was stopped for lunch last week and measuring the temperature of the sidewalls of my trailer's tires, another RV'er (motorhome) asked me what range was I looking for. I told him, truthfully, I wasn't sure but I thought if the temperature seemed too outrageously hot I kind of recognize it. I know the blow-out temperature for semi tires is about 300F from a recent episode of Mythbusters. At what temperature should I get concerned?

[millvalleyca]

Now I have to go out and buy an infared thermometer to measure the temp of my tires?!
One more thing to worry about?

[HiHoAgRV]

Originally Posted by millvalleyca

Now I have to go out and buy an infared thermometer to measure the temp of my tires?!
One more thing to worry about?

Keep checking back and we, your faithful peanut gallery, will have your mind awash with techno fodder!

As covered above, download the pressure/weight chart for your trailers and TV's tires. Check your weight and inflate accordingly using the method recommended by the manufacturer (cold, correct?). I bought an infared thermometer to play with. The laser drives the cat crazy.

BTW, my TV's tires are max rated at 80 PSI but the fully loaded correct pressure, while towing, is 55 psi. Quite a difference, huh?

[Beginner]

millvalleyca
If you have the ST tire other than the Cooper Custom Trailer Plus, run them at max pressure. This minimizes the sidewall flex and hense the heat build up in the tires. More importantly slow down.
Slowing down will also slow the heat geneeration.
Slow down how much? I dont know.
My tires are speed rated to 99 MPH. At 65 I have a 34% safety margin.
To attain that same safety margin you would have to do 43 MPH with the ST tire(except for the Cooper Custom Trailer plus).

I see a number of failures on the forum but somehow they don't seem to be turning up on the National Highway Transportation Safety Administration web site.
If you have a tire failure report it at this web site:

IVOQ - File a Complaint

Do us all some good.
Beginner

[silverback]

Minnie's Mate,
There was a recent post regarding the IR/laser temp gauges (available at Harbor Freight) that I think had the temperature ranges. I'll search for it.
-KL

[HowieE]

Originally Posted by Minnie's Mate

Does anybody know how hot is too hot for the tire temperature?

I carry a Radio Shack infar red thermomator more for checking bearing temperature than tires. As for tires, just after I pull into a rest area I touch each sidewall of the tires. If I can hold the tire I am happy. Those that I have measured witht he thermomator generaly ru about 110 degrees F. Keep in mind that if you are traveling across the sun the tires on the sunny side will be about 10 degrees hotter than the shady side. Just a fact of nature.

If you touch a tire that has ply seperation and is about to go you will know it by the touch.

If I want to test the bearings I will coast into the rest area without using the trailer brakes. Having done that and if I find a Hot Hub I know I either have a bearing problem or a dragging brake.

[millvalleyca]

OK....I printed the inflation chart that HowieE made available.
How do I read it?
Find my tire size on the chart.
Single (S) or Dual (D)...I have four tires so the "Dual"?
The lbs represent per tire weight??? Times the number by four?
Does anyone have an "etimate" as to how much my trailer might weigh?
We have the regular stuff in the trailer for 2 adults and 2 kids. Nothing overly heavy and not filled to the brim.
Thanks AGAIN!

[Minnie's Mate]

I have never NOT been able to hold my hand on the side walls of my tires. When I used my infrared thermometer on this last trip I found, as you say, a 10F difference between the sunny side and the shaded side of the trailer. I figured since the temps were lower than the tow vehicle's tire temps and way below the 300F that the Mythbusters show said was the blow-out temp for semi tires (I know, big difference between an Airstream and semi), that I was probably OK. But I'm just curious, at what point should I start to worry?

[millvalleyca]

Hi Minnie's Mate
Family of Disney Fanatics?
We're off to Disneyland this Sunday for 5 days!
..........if I get my tires at the right pressure!

[HowieE]

Originally Posted by millvalleyca

OK....I printed the inflation chart that HowieE made available.
How do I read it?
Thanks AGAIN!

For a starter look at the tag on the side of your trailer. It will have a "Gross Vehical Weight". For the sake of arguement lets use that for now.

If you have 4 tires devided that GVW by 4. That will give you the load each tire is carrying. Now find your tire size on the chart and read across till you see a weight just above the calculated load. That will work untill you have a chance to take your trailer to a scale and weight it loaded as you are when traveling. I expect your loaded weight while traveling will be less than the GVW unless your are a pack rat or have bougth one of the new Airstreams that can only carry 40 lbs. of additional load.

That's another topic that should get as much attention as the Goodyear Marathons

[millvalleyca]

Thanks HowieE....nice and simple!
Next question....
What are the steps for weighing my trailer?
I can pull into any "weigh station" on the side of the road? How much do they charge?

[Cracker]

The tag on the lower front curbside also gives the correct tire size and inflation pressure and allowable axle load - unless Airstream has changed something. I would weigh as soon as I could get to a scale to make sure I'm not overloading the axles, but you won't go wrong, tirewise, using Airstream's recommended pressure. It will very likely be the max design pressure for the tires that came with the trailer, as it was for my 2000 30' Excella until I went up to the next higher tire rating.

[jcanavera]

Originally Posted by HiHoAgRV

Keep checking back and we, your faithful peanut gallery, will have your mind awash with techno fodder!

As covered above, download the pressure/weight chart for your trailers and TV's tires. Check your weight and inflate accordingly using the method recommended by the manufacturer (cold, correct?). I bought an infared thermometer to play with. The laser drives the cat crazy.

BTW, my TV's tires are max rated at 80 PSI but the fully loaded correct pressure, while towing, is 55 psi. Quite a difference, huh?

Yep but not surprising. On my 3/4 GMC van, I'm using E rated tires. Recommended pressures for max capacity on the van is 80 lbs in the rear 55 in the front.

Jack

[HowieE]

Originally Posted by Cracker

The tag on the lower front curbside also gives the correct tire size and inflation pressure and allowable axle load - unless Airstream has changed something. I would weigh as soon as I could get to a scale to make sure I'm not overloading the axles, but you won't go wrong, tirewise, using Airstream's recommended pressure. It will very likely be the max design pressure for the tires that came with the trailer, as it was for my 2000 30' Excella until I went up to the next higher tire rating.

Please Cracker, unless you are a lawyer for Airstream stop giving out missinformation. I have repeatedly asked individuals to use the information posted by the manufacture of what ever tire they may be using. That information is the result of extensive testing by engineers that far exceed our talents. Only on a single axel trailer will the stated tire pressure stated on the Airstream tag ever even be close to what you should be using. And if that is close it is only because Airstream under designed the axel and undersized the tires.

[HowieE]

Originally Posted by millvalleyca

Thanks HowieE....nice and simple!
Next question....
What are the steps for weighing my trailer?
I can pull into any "weigh station" on the side of the road? How much do they charge?

I have used government scales in Canada but would not suggest it in the States what with Home Land Security.

Go to any truck stop or moving van company and ask them to weigh you. Idealy if you have mor ethan one axel tell them you will pull on the scales with just the TV first, once weighed pull forward till the first trailer axel is on the scale, and then pull on till the next axel is on. If you have a third axel repeat till you have all axels weighed. Now some subtraction will give you the weight of each axel. I say weigh each axel to cover you if the trailer is not riding level. Once you have the math done you can select your tire pressures per axel or if the are close use the heavier one. I geneeraly go one step higher on the chart just to cover what we may buy on the road or if we are cought hauling a full set of tanks.

As a point of information. Over inflated tires will wear in the center of the tread just as underinflated tires will wear on the outsides, if they last that long before a blowout. If you see wear on one side only your axel is missaligned.

Good Luck

[jcanavera]

One other source for weighing your trailer is RV Self. This safety organization puts on seminars at many rallies and other areas. I had my Safari weighed at a SOB dealer who sponsored a safety seminar. They place a scale under each tire to give you an accurate picture of the load on each tire. They do the weighing while hooked to your tow vehicle and unhooked.

You probably can go to their web site and get a list of locations where they will be at. Here is the link to their site. RV Safety:


They talk a lot about motorhomes since overloading seems to be a big problem in that side of the RV world. Once you have been weighed they give you an initial report, plus you get a detailed analysis in the mail at a later date.

Jack

[millvalleyca]

Hi guys
Just got home and checked my tires
GVW of trailer is 7,000
divided by 4 = 1750
tires on trailer ST225/75R15
max speed rating 65
max psi 65
move along the chart
1760 is 30 psi
1880 is 40 psi

If I use these numbers it seems like my tires will be VERY mushy
Right now they're at 49-52 psi


Now what?
Am I missing something?

[LI Pets]

Originally Posted by millvalleyca

Hi guys
Just got home and checked my tires
GVW of trailer is 7,000
divided by 4 = 1750
tires on trailer ST225/75R15
max speed rating 65
max psi 65
move along the chart
1760 is 30 psi
1880 is 40 psi

If I use these numbers it seems like my tires will be VERY mushy
Right now they're at 49-52 psi


Now what?
Am I missing something?

Ok you're at third base, you understand that the 4 tires may very well not distribute the weight exacly even at 1750, so go with 1880 that gives you a 400 lb cushion. Or go to the next load I guess it's 1900 something at 50psi.

That is pretty correct to go 65 MPH, now if you want to go faster than 65 you add 10psi to bring the speed rating to 75MPH.
This is according to written specs by Goodyear and all others.

Bottom line I would use 55-60 PSI and feel very safe.

Happy camp'n

[Cracker]

Originally Posted by HowieE

Please Cracker, unless you are a lawyer for Airstream stop giving out missinformation. I have repeatedly asked individuals to use the information posted by the manufacture of what ever tire they may be using. That information is the result of extensive testing by engineers that far exceed our talents. Only on a single axel trailer will the stated tire pressure stated on the Airstream tag ever even be close to what you should be using. And if that is close it is only because Airstream under designed the axel and undersized the tires.

You lost me on that one HowieE! Unless there are great differences between manufacturers of specific size and rated tires (---which I don't believe is true) I believe that using the inflation data provided by Airstream, and sticking to the recommended tire size - or those correct tire sizes, with a higher load rating, is just about as safe as you can get - provided you weigh the trailer to make sure you are within the design load range of the axles - which the tires have been sized to accommodate. The only thing you can do beyond that is to "individually" weigh each tire and axle if you can find the resources to do so. I believe that Jack provided information in post #36 about a group that provides that service. For the record, I do use the tire charts provided by Goodyear for the Marathon tires. By no means have I placed myself in a superior position to the engineers that designed our Airstreams - or, for that matter, in any position that implied that I was suggesting an alternative to using available engineering data. I invite you to read other comments I have made on this matter and, if I am in error, I will be more than happy to accept your findings and apologize for providing erroneous information. Kindly re-visit your comment about my giving out "misinformation."

[millvalleyca]

Thanks guys
I guess I'll just fill the tires to 55 psi!
Off to Disneyland we go