Which Tire Pressure to Follow?

[Jakieboy]

Trailer tires rarely wear out or fail from excessive mileage. In more that 40 years of Rv-ing, we have only had tire failures from punctures, slow leaks, and several from poor construction (China Bombs). We live in Long Beach, CA, at sea level. When we leave for a long trip, when we know we are going into higher altitudes, we start with all tires at max recommended pressure, then adjust downward as we go up in altitude. As we go downhill, we stop at regular intervals to boost the tire pressures as necessary. We've done this for decades. So far, no tire failures for under or over-pressure conditions. Tire wear looks great for both trailer and TV. In our experience, max tire pressure on trailer and TV tires has little or no effect on ride quality. Everything in our 5th wheel survives, even on some pretty rough roads. We do take a bit of care to drive gently.

[Papahoosh]

Thank you all for your input, I am more confused than before from reading all of those good infos, you guys are awesome. I had the tire pressure set for 65 PSI for now, figured go in between. I email the manufacture to find out the wheel rating.

[Tireman9]

Originally Posted by rsdata

Tireman9...

appreciate your input from an expert...

from reading here near the bottom of the blog
RV Tire Safety: "Interply Shear" and other Techno Babble

I find this information on the blog...



So now I am confused as you state in your answer to use calculations of 115% and 10%... ( I can do the math) which seems to support inflation pressures below the MAX for trailers with lighter weights that upgraded tires are intended to support.

So which is right? MAX or calculated minimum pressure per your answer.

thanks in advance for your attention to this forum...

Some folks refuse to run tiresidewall pressure. Also some will discover that once they learn the actual weights the tires are overloaded even when inflated to the sidewall pressure.

I am just trying to offer advice from two directions in an effort to decrease the rate of tire belt separations.

Key is to first confirm the actual weight on heavier end of each axle when the RV is fully loaded.

[aircommuter]

Tireman is right, I owned dump trucks for years, and we couldn’t lower the air pressure everytime we dump a load of rock which weighed more than the truck’s unladen weight. Many pressure charts are for ride, not durability, safety, or tire wear. You are safer running higher than low. Low equals flex that equals heat, that equals failure.

[Murbella7]

After a few months sitting idle, I went to get my Silverado out to set it up for our next trip. Rear tire was flat. Spare was flat. Hhmmm is this a problem. Pumped up both tires but as a check, took them up to a well known (here in Oz) tire dealer for testing. They wanted to charge me $60 per wheel. One guy also told me that I should be lowering my tires from 70psi to 50 when I have no load on. The pump them back to 60 for running.

My rears are 'E' rated, at 80psi, this guy was supposedly an expert but obviously knew next to nothing. I am not sure he is typical, but it seemed to be the same opinions with the rest of the staff there. I went down the road about a 300 feet to another dealer who checked both the rear and spare for nix and refuted the other guy's opinion. He said it is more trouble that it's worth and may in fact cause more problems constantly changing tire pressures, not that I would.

[aircommuter]

i can't imagine how much it would cost for trucking fleets to do that, just UPS alone would be a lot of money, and they would probably have to get a service person to do it as union workers can't go outside their job description.
That is like saying when the load is removed the tires can't hold as much pressure, putting lots a miles empty at full pressure could increase wear.

I have found in the mountains where I live if I run more than 15% below max my tires wear the outsides down prematurely, a combination of the cornering and the rough seal coat applied to our roads. Truck, trailer or car all the same for this situation.

[Tireman9]

Originally Posted by Murbella7

After a few months sitting idle, I went to get my Silverado out to set it up for our next trip. Rear tire was flat. Spare was flat. Hhmmm is this a problem. Pumped up both tires but as a check, took them up to a well known (here in Oz) tire dealer for testing. They wanted to charge me $60 per wheel. One guy also told me that I should be lowering my tires from 70psi to 50 when I have no load on. The pump them back to 60 for running.

My rears are 'E' rated, at 80psi, this guy was supposedly an expert but obviously knew next to nothing. I am not sure he is typical, but it seemed to be the same opinions with the rest of the staff there. I went down the road about a 300 feet to another dealer who checked both the rear and spare for nix and refuted the other guy's opinion. He said it is more trouble that it's worth and may in fact cause more problems constantly changing tire pressures, not that I would.

1. Your experience is why it is suggested to check the air at least once a month.

2. Why were they "flat". Leaking valve? leaking valve core? punctures? poor wheel seal? It would be good to know as there is no rational reason for a tire/wheel assy to loose more than 3 - 4% a month unless something is leaking.

3. many guys that sell tires think they are tire engineers. NOT.

4 It would help to know at least the axle load when not towing and when loaded and hooked up for ltowing. Yes some feel that inflating each time they hook-up is a pain so they either do not. or they think they can split the difference. Neither of these options is good.

5 I can not think of any reason why adjsuting the inflation for the load would be bad for the tire. It takes effort on yourpart buy I can't see it hurting the tire at all.

6. Find out why the tires went flat. Are you sure there are no sidewall cracks on the rear tire that went flat.

7 Look at the sidewall cracks on my tire.
HERE.

[Murbella7]

Originally Posted by Tireman9

1. Your experience is why it is suggested to check the air at least once a month.

2. Why were they "flat". Leaking valve? leaking valve core? punctures? poor wheel seal? It would be good to know as there is no rational reason for a tire/wheel assy to loose more than 3 - 4% a month unless something is leaking.

3. many guys that sell tires think they are tire engineers. NOT.

4 It would help to know at least the axle load when not towing and when loaded and hooked up for ltowing. Yes some feel that inflating each time they hook-up is a pain so they either do not. or they think they can split the difference. Neither of these options is good.

5 I can not think of any reason why adjsuting the inflation for the load would be bad for the tire. It takes effort on yourpart buy I can't see it hurting the tire at all.

6. Find out why the tires went flat. Are you sure there are no sidewall cracks on the rear tire that went flat.

7 Look at the sidewall cracks on my tire.
HERE.

1: I check often but not regularly. I don't actually put a pressure gauge on them each time but do a visual check. You get reasonably good at noticing things like a partially deflated tyre after a while. If I am about to hook up for a trip, then we do a full pre-flight, on everything.

2: After a thorough check of everything at the tyre place, nothing out of the ordinary was found. The suggestion from the guy was that it was 'typical/normal' for heavy vehicle sitting idle for a few months for a tyre to leak a little (even though mine had leaked a lot). "The tire gets a bit hard and develops 'weak' spots where air might leak". He stressed it was only a suggestion. I will be keeping an eye on them. That was last month and they have not deflated any since. I am due to roll out Monday morning so will be doing a thorough pre-flight on Sunday.

3: Oh, how true is that. The only thing they have in their favour is experience. Most tyre guys do get some training but that is mostly differentiating between the various tyre types to give them sales leverage.

4: I did that some time ago but seems I didn't write it down and store it somewhere I can remember. Still, I do know that my chevy weighs about 4000 kg or 4.4 ton.

5: I agree it wouldn't really hurt the tyre, just my aging back. Compressor is locked in the chevy tool box. Getting in and out of the tub is an exercise in itself, so I minimise that. Can't really see any huge advantage in deflating/inflating because the chevy doesn't do any day work, just the odd heavy or long load stuff and towing.

6: As I said, a thorough leak check was done as well as visual inspection of all parts, tread, sidewalls, beads, internals, etc.and no cracks. Very little feathering on the inside tread edge.

7: Saw that earlier and yes, noted. These are pretty new tyres. Yes they have now done just over 20,000kms, or just under 12.5k miles, but again, I'll keep checking. And no, they have nothing like the wear marks yours did.


I checked the label on the 5'er again today and FR is trying to tell me that max loaded weight should not exceed 4.5 tonnes, with the axles, rim, tyres supplied. At 4.1 tonnes empty, that leaves just enough room to add a bottle of milk and a tea bag. No wonder my original tyres failed. We would have been way over that pulling out of the driveway for the first time.


Anyway, after the first couple of disasters were accommodated, we should be pretty right from now on.

[Murbella7]

Originally Posted by aircommuter

i can't imagine how much it would cost for trucking fleets to do that, just UPS alone would be a lot of money, and they would probably have to get a service person to do it as union workers can't go outside their job description.
That is like saying when the load is removed the tires can't hold as much pressure, putting lots a miles empty at full pressure could increase wear.

I have found in the mountains where I live if I run more than 15% below max my tires wear the outsides down prematurely, a combination of the cornering and the rough seal coat applied to our roads. Truck, trailer or car all the same for this situation.

I think vehicles that on the road fairly constantly would not have these issues.

[Tom48]

Originally Posted by aircommuter

Tireman is right, I owned dump trucks for years, and we couldn’t lower the air pressure everytime we dump a load of rock which weighed more than the truck’s unladen weight. Many pressure charts are for ride, not durability, safety, or tire wear. You are safer running higher than low. Low equals flex that equals heat, that equals failure.

Ditto

[Tireman9]

Originally Posted by aircommuter

i can't imagine how much it would cost for trucking fleets to do that, just UPS alone would be a lot of money, and they would probably have to get a service person to do it as union workers can't go outside their job description.
That is like saying when the load is removed the tires can't hold as much pressure, putting lots a miles empty at full pressure could increase wear.

I have found in the mountains where I live if I run more than 15% below max my tires wear the outsides down prematurely, a combination of the cornering and the rough seal coat applied to our roads. Truck, trailer or car all the same for this situation.

Can't respond to the "I run more than 15% below max " as the numbers on the tire are simply advising of the max load capacity at a given inflation. Since we don't know your real laods,we don't know the minimum air you need to run.
Maybe 15% or even 20% below the tire number is OK based on your actual tire loading.

[Mtelkman]

Wow. Lots of bad info in this thread. Listen to Tireman9. He is one of the few who know about what they speak.