Tire pressure question.

[w2much]

Just blew out some tires which were inflated to the recommended max of 50 pounds. I have in the past kept them at about 35 to 40 psi. I used them for a few years at this lower pressure without issue. After reading on this forum and checking the tires I decided to fill them to 50 pounds. I just put a new set of 4 Goodyear marathons on and am wondering should I keep the pressure to the max(50 pounds ) or go back to 35-40 pounds as I have in the past. I am hoping to tow the boat 1000 miles RT this summer and want to get it right. Loadmaster aluminum trailer,dual 3500 #eliminator torsion axles, 4 new Marathon tires rated at 1360 each, boat weighs about 3500#'s with motor and gear.

 

[Bondo]

Re: Tire pressure question.

Ayuh,.... I blow 'em up to the #s stated on the sidewalls,...

You can do whatever ya please,... It's yer trailer....

'ell, I had my houseboat wagon tires Foam Filled...
'course, it only moves a 100 yards a year...

 

[etracer68]

Re: Tire pressure question.

General rule of thumb is, if the tire wears in the the center more, you are over inflated. If the tire wears more on the outsides, then you are under inflated. If they where mine, I would go for the max pressure to start, run on the highway about 10 miles, stop and look at the tires, you should be able to see the wear pattern on new tires easy.

 

[bigdee]

Re: Tire pressure question.

Just blew out some tires which were inflated to the recommended max of 50 pounds. I have in the past kept them at about 35 to 40 psi. I used them for a few years at this lower pressure without issue. After reading on this forum and checking the tires I decided to fill them to 50 pounds. I just put a new set of 4 Goodyear marathons on and am wondering should I keep the pressure to the max(50 pounds ) or go back to 35-40 pounds as I have in the past. I am hoping to tow the boat 1000 miles RT this summer and want to get it right. Loadmaster aluminum trailer,dual 3500 #eliminator torsion axles, 4 new Marathon tires rated at 1360 each, boat weighs about 3500#'s with motor and gear.

You answered you own question...."you ran them at lower pressure for several years" Two things may have happened; damage from improper inflation or old age.....most likely a combination of both.

 

[Silvertip]

Re: Tire pressure question.

You need to start an investigation. Two 3500# axles means they have a total capacity of 7000# but ONLY if the tires also have that capacity. You have four tires with a combined load capacity of 5440#. You have a trailer that probably weighs about 800 - 900# empty. So lets do some math. 900 (trailer) +3500 (boat - estimated and usually wrong) = 4400#. I would assume the boat generally contains coolers, gear, anchors, batteries, and a host of other stuff that adds up quickly not to forget about 40 gallons or so of fuel at another 300#. You indicate you ran the tires at 35 - 40 PSI which means you ran them very much "under inflated" for the total GVW. Does it make sense that the original tires were damaged by underinflation and when finally inflated to 50 PSI that is what did them in? People generally grossly underestimate the weight of their rigs. The only way to know what you have is to load it up as you normally would and have it weighed. Regardless of the outcome, air those tires up to the marking on the sidewall. That is the ONLY way they can support the rated capacity. There is one issue with tandem torsion axle trailers that may have a bearing on tire failure. Unlike leaf spring tandem axles, torsion axles do not have the "walking beam" that allows individual wheels to "step" over "or into" obstructions without altering tire loading. Yes - torsin axles do have independent spindles but here is the rub. Entering and leaving a gas station for example or a driveway can result in one axle being extremely "unloaded" which obviously transfers that weight to the other axle. Since most boat trailers are typically loaded close to the maximum GVWR or the trailer itself or the tires (as in your case), every time you do this with underinflated tires you overload those tires even more. I very frequently see long torsion axle tandem trailers (loaded or unloaded) make a turn onto sharply different grades and one axle is off the ground untill the entire rig gets level again. It is therefore critical that you tow this trailer (adjust the hitch height if necessary) so the rig tows dead level. This concept may be little hard to get your head around but it happens.

 

[raycraft92]

Re: Tire pressure question.

I work at a mount and dismount tire sirvice, my advice to you is to air them up to the mark on the sidewall of the tires, then let out about 5 pounds of pressure, it will save the tires tread more than just filling them up to the maximum mark.
good luck.

 

[bigdee]

Re: Tire pressure question.

A good rule of thumb is to inflate to max pressure. We all know that under-inflation can damage tires...max inflation does not cause any issues so why not set it at that and forget it? Trailer tires wearing from max pressure is hogwash....the tires will dry rot before then, especially for the normal recreatioal boater. Tires should be replaced every 3 or 4 years regardless of how they look.

 

[oregoncruiser]

Re: Tire pressure question.

One problem with max air pressure on boat trailers is ride quality. Newer trailer with torsion axles just don't ride like the old tandem axle leaf suspension trailers. I run mine about 5 lbs under max just to try and salvage the ride a little bit. I also just drive slower in order to help ride quality, and to help keep the heat down.

On my flatbed trailer I run max pressure, but that trailer is usually loaded close to maximim, or over max, LOL!!


I understand the idea that tire flex creates heat and therefore you should run max pressure, but I also don't want to beat my boat apart when I hit that unexpected bump in the road.

 

[bigdee]

Re: Tire pressure question.

One problem with max air pressure on boat trailers is ride quality. Newer trailer with torsion axles just don't ride like the old tandem axle leaf suspension trailers. I run mine about 5 lbs under max just to try and salvage the ride a little bit. I also just drive slower in order to help ride quality, and to help keep the heat down.

On my flatbed trailer I run max pressure, but that trailer is usually loaded close to maximim, or over max, LOL!!


I understand the idea that tire flex creates heat and therefore you should run max pressure, but I also don't want to beat my boat apart when I hit that unexpected bump in the road.

Your boats takes alot more pounding and abuse on choppy water than on a trailer but if I was really concerned about it I would install shocks on the trailer rather than playing with tire pressure.

 

[Silvertip]

Re: Tire pressure question.

AA load that is too heavy for the trailer is a problem. A trailer that is rated for loads far heavier than the actual load is a problem. Boat trailers are typically loaded at 75% to nearly the maximum GVWR (and in many cases it is way over the GVWR). That requires maximum inflation pressure for the tires. And when replacing tires, they must have a load capacity equal to or greater than the trailer GVWR or that number must be downgraded to the capacity of the tires.

 

[w2much]

Re: Tire pressure question.

The old tires were dated 2005, the year of the trailer. Thanks for all of the input. I tend to think that the age and underinflation over time were probably the cause of the failures. I will bring them to 50# or a few less.Thanks again.

 

[Silver Eagle]

Re: Tire pressure question.

What is the load range of your tires. Mine are D's and my tires are on ten inch wheels and I use 50lbs. Soomething like an c range tire would probable blow out. It's a heat thing.

 

[impatico]

Re: Tire pressure question.

I have been a tireman for MANY years. worked on EVERY tire imaginable and was the guy responsible for training all the new guys.

every travel/utility/boat trailer at some point had a recommended tire inflation pressures placard. they always say to max out the tire pressure if you are running reccomended tires. trailer tires are designed way different than passanger so you can't really gauge by tire wear. what I would do is pump them up to 50 and look at the tires, if they are still a little bulge at the bottom leave them as when you use the trailer it's going to have even more weight on them.

Oh and don't worry about them blowing as any decent tire shop warranties trailer tires for the life of them. if they blow after you wore off 20% you pay for 20% of a new tire, the shop I was at would even warranty the other tire on the same axle to get you 2 new so they are matched if you wanted

 

[dingbat]

Re: Tire pressure question.

I would suggest you read the Goodyear Service Bulletin for Marathon ST rated tires. They give very detailed inflation requirements for the tire based on max. speed, not weight!!

http://www.tirerack.com/images/tires/goodyear/Marathon_Special_Trailer_Applications.pdf

 

[impatico]

Re: Tire pressure question.

I hope he's not doing 75 MPH with a dual axle boat trailer LOL

 

[H20Rat]

Re: Tire pressure question.

I would suggest you read the Goodyear Service Bulletin for Marathon ST rated tires. They give very detailed inflation requirements for the tire based on max. speed, not weight!!

http://www.tirerack.com/images/tires/goodyear/Marathon_Special_Trailer_Applications.pdf

Read it again, you skipped the part where they mention load I guess... They mention weight twice for a very specific reason... I know this is a hornets nest, but you should roughly match load to air pressure. If the tire is rated at 1500# at 80 psi, there is no reason to run that much if you have 500# on it. (and no, it does not scale in a linear fashion, so 1/3 of the capacity doesn't mean 1/3 of the air)

The idea is to to run with the entire tread on the ground. Too much air/too little load and you only run on the center of the tire. This wears the tire out, as well as compromises traction. The tire itself was designed with a specific amount of flex at max load/max psi, by running at less than max load, you are not using the tire for its design. A tire that is properly filled at less than max load will last longer and is safer than one at max PSI.





Industry standards dictate that tires with the ST designation are speed rated at 65 MPH (104 km/h) under normal inflation and load conditions.

Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

 

[JimS123]

Re: Tire pressure question.

Read it again, you skipped the part where they mention load I guess... They mention weight twice for a very specific reason... I know this is a hornets nest, but you should roughly match load to air pressure. If the tire is rated at 1500# at 80 psi, there is no reason to run that much if you have 500# on it. (and no, it does not scale in a linear fashion, so 1/3 of the capacity doesn't mean 1/3 of the air)

The idea is to to run with the entire tread on the ground. Too much air/too little load and you only run on the center of the tire. This wears the tire out, as well as compromises traction. The tire itself was designed with a specific amount of flex at max load/max psi, by running at less than max load, you are not using the tire for its design. A tire that is properly filled at less than max load will last longer and is safer than one at max PSI.





Industry standards dictate that tires with the ST designation are speed rated at 65 MPH (104 km/h) under normal inflation and load conditions.

Based on these industry standards, if tires with the ST designation are used at speeds between 66 and 75 mph (106 km/h and 121 km/h), it is necessary to increase the cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.

Finally somebody gets it right!

You read online about all the misfortunes on the highway. Its no wonder with all this misinformation published.

 

[impatico]

Re: Tire pressure question.

You can read online all you want, but the BEST thing to do is find that tire placard, it's a 2005 it should have one with a couple different pressures for a couple different loads

worth a shot, most the newer one have them

Oh and NEVER just pump up a tire to what it says on the sidewall, that is the MAXIMUM pressure, not the recommended pressure. There should always be a tire inflation placard somewhere, the door jam, owners manual, some on the fuel door. Unless you have a very different tire size than is says on there go with it.
for your guys trucks the bigger the tire the less are, I have 40PSI in my diesels tires, and I tow a lot!

 

[bigdee]

Re: Tire pressure question.

You can read online all you want, but the BEST thing to do is find that tire placard, it's a 2005 it should have one with a couple different pressures for a couple different loads

worth a shot, most the newer one have them

Oh and NEVER just pump up a tire to what it says on the sidewall, that is the MAXIMUM pressure, not the recommended pressure. There should always be a tire inflation placard somewhere, the door jam, owners manual, some on the fuel door. Unless you have a very different tire size than is says on there go with it.
for your guys trucks the bigger the tire the less are, I have 40PSI in my diesels tires, and I tow a lot!

TRUE for cars & rucks....not true for trailer tires

 

[impatico]

Re: Tire pressure question.

TRUE for cars & rucks....not true for trailer tires

True for every tire out there, what part isn't true for trailer tires?