Tire inflation, what temperature is "cold"

We have our original import tires on our 2021 and were going to replace them after this season. A lot of people call them bad tires but I think they don't keep them inflated properly and drive too fast and they pop.
Good to hear the Carlisle's are decent as those and the Maxxis are on top of my list. I didn't know if buying the Goodyear Endurance was worth spending extra on. My mechanic loves the Maxxis for his camper. Carlisle seems to be readily available and decently priced.
 
Wayne said:
I believe heating caused by under inflation is the number one cause of blowouts. @CapriRacer will know.
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First, we tire engineers don't like the term "blowouts". The term is used in the public arena in so many ways, including times where the tire stays inflated.

The number 1 reason for tires being removed from service is they are worn out. I don't know what percent that is, but it's about 80%. About 15% of the tires get a puncture in their life, but most are repaired and will wear out.

But we're talking about RV tires here - and there are 2 groupings according to the way they end their life.

There's a group that behaves like other tires and then there are ST tires. For some reason that I don't understand, trailer manufacturers don't seem to learn the same lessons manufacturers of vehicles with engines learn.

What trailer manufacturers do is put the minimum tire size on. Further, they tend to buy tires based on price. So for a period of time, ST tires were manufactured in China when Chinese tires were just entering the US market - that is before they figured out how the game is played - and the way it is played is that tires have to exceed the government minimums by a substantial margin in order to perform adequately. Those Chinese tires performed pretty badly and where they were most obviously present was on trailers. It was a niche market that few tire manufacturers made tires for.

Further, ST tires require more inflation pressure than the light duty tow vehicles, so many of those tires were underinflated. The net effect was that there were many failures of the "blowout" kind and it was hard to determine if the cause was an inadequate tire design or underinflation.

But today things are different. The trailer manufacturers are doing a better job of sizing tires. The tire manufacturers are doing a better job of designing tires and users are doing a better job of inflation maintenance.

And even then, ST tires seem to be behaving differently. They aren't failing as often, but they are failing much later in life. What I think needs to happen is for trailer manufacturers to go one more step up in size. Better yet, go up 2 steps and use less inflation pressure so the ride is better for the contents of the trailer.
 
Another satisfied Carlisle Radial Trail HD buyer here.

My trailer probably weighs about 5500 to 6000 pounds these days, my tires are SKU "6H04561" and rated at 2040 lb/tire with 65 max psi.

I generally make sure they're at 55 psi before setting out, does anyone feel this would be problematic?
 
FrozenNorth said:
Another satisfied Carlisle Radial Trail HD buyer here.

My trailer probably weighs about 5500 to 6000 pounds these days, my tires are SKU "6H04561" and rated at 2040 lb/tire with 65 max psi.

I generally make sure they're at 55 psi before setting out, does anyone feel this would be problematic?
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Does Carlisle publish load tables?
 
@FrozenNorth go to the link that capriracer posted above and look for your tire size - the chart will show you the proper inflation for the weight the tire is carrying. That's the pressure you should run.
 
Thanks guys, so using this:

ST205/75R14 Tire Pressure Chart

Proper tire load capacity at recommended tire inflation pressures and rim diameter for ST205/75R14 tires.
tirepressure.org tirepressure.org

Then I take my trailer weight at 6000 pounds, subtract 800 for tongue weight and I'm at 5200. divide by 4 to get 1300.

Fudge factor, say 1280 to 1350.

That means I should be running 25 psi to 35 psi?

Sounds very low.
 
FrozenNorth said:
Thanks guys, so using this:

ST205/75R14 Tire Pressure Chart

Proper tire load capacity at recommended tire inflation pressures and rim diameter for ST205/75R14 tires.
tirepressure.org tirepressure.org

Then I take my trailer weight at 6000 pounds, subtract 800 for tongue weight and I'm at 5200. divide by 4 to get 1300.

Fudge factor, say 1280 to 1350.

That means I should be running 25 psi to 35 psi?

Sounds very low.
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Ah...... Mmmmm ....... Not exactly. You forgot to account for side to side and front to rear weight variation. Here, I tell how to do this: Barry's Tire Tech: ST Tires

The starting point ought to be the vehicle tire placard. Then make modifications from there. Don't forget the Tire Pressure Buildup Test to confirm.
 
Ppl
Wayne said:
For Frozen's tire size of ST205/75R14 after adding 15% I get 40 psi. @CapriRacer does that sound right?
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No, it doesn't sound right. It's too far away from the 65 psi max. I would expect the value to be much, much closer. I did notice you didn't account for side to side and front to rear weight variation.

There is so much we don't know about Frozen's situation. How did he come up with the 6,000# value? What does the placard say? Do we trust the placard?

And before doing anything else, I'd like to see the results of the Pressure Buildup Test. Barry's Tire Tech: Pressure Buildup Test
 
Here is my trailer sticker. Dry weight in lbs is 4173, I often travel with full fresh water, and I'm estimating the weight of the cargo. These days I probably don't exceed 5500 lbs but I have hauled a bit more in there (taking a bunch of stuff home from the leased pad where it was staying all summer etc) a few times so that's where the extra 500 was giving me the range of 5500 to 6000.

I will do the pressure test next time I set out which should be fairly soon.

placard.jpg
 
Our TT came with 205/75-15 D’s but when I replaced them, I went to 225/75-15 E’s. Max pressure for the D’s is 65 lbs and 80 lbs for the E’s. We’re running right at 7000 lbs gross weight including tongue weight. The D’s would have been enough but I wanted a little extra margin so went with the E’s since it was only about $10 a tire. I run mine at 70 psi cold and they roll easy and ride very good. I also had them balanced and metal valve stems installed. When we’re traveling, we usually stop every 2-3 hours and I check the temperature of the tires and the hubs. I don’t use an IR thermometer, just my hand. I’ve been at this tire thing for a long time being retired from the trucking industry. Preventative maintenance is where it’s at.
 
Wayne said:
OMG, I learned something today!!! I had no idea the load tables are standard... wow
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well, its fairly standard engineering process to come up with the tables.. figure a given size tire has a certain volume or surface area, and multiply that by the air pressure and you come up with an amount of force.. not unlike brake chambers in HD vehicles... they have a type... say type 30 or type 36, which indicates the square inches of the surface area inside the chamber... so a type 36 which could theoretically get 100 psi of air pressure on a full brake application could exert 3600 pounds of force on a braking mechanism. Take any tire, if you know how many cubic inches of air it holds, and know the pressure inside you realize how many thousands of pounds of force are contained in the tire... that is why they sometimes explode.. funny thing is most of us dont realize we are riding around on a potential bomb. :)
 
@CapriRacer, you reference front to back and side to side differences of weight on the trailer tires. Our trailer came with side to side weight numbers. If a trailer sits level when hooked up how much weight difference could there be on the axles?
 
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