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Discussion in 'Tires / Brakes / Bearings / Axles' started by Enigmacamper, Jun 12, 2019.
How do you figure that out? I always thought you had to have max pressure in the tires?
The rating is usually not expressed in maximum. It displays the tire pressure that will allow the rated weight. You should inflate to that. Can you show us how to derate the pressure for some other load? For example if a tire is rated Maximum load: 1,360 lbs at 50 psi. can you tell me the pressure for 1000 lbs.? The tire should be inflated to 50 psi. Do it.
Example, from the web
5.30-12 4 inch rim … my wheels
Load Range B: 840 lbs at 55 psi
Load Range C: 1,045 lbs at 80 psi (5.5 Bar) … my tires
Load Range D: 1,250 lbs at 105 psi
my wheel load is nearer to 600-700 Lbs max (I think) so I elected to use 65 psi - the tires look fine at this load-pressure combo (though it might have been a bit too much). I checked their temperature several times - they only got really warm if it was hot outside (like 100 deg F in NV)
Always inflate trailer tires to the max psi on the sidewall. It's not just about the load. The tires were designed to be inflated and used at the max pressure. Every shop and tire manufacturer says the same thing.
I think his work better a little deflated because of the bias tires. Bias are stiffer in general. So to get a smoother ride they dont run them at max pressure, just whats needed? Just an idea.
Car tires and trailer tires are different. It is commonly accepted that trailer tires should be at max pressure. I went up one load range for my camper. The Carlisle radialtrail are hard as rocks to begin with. So in my case, max pressure was just a bit too much and was beating the hell out of the camper. Dropped back to 60psi from 65psi. The camper rides much more smoothly now. I also used to notice the center bead was hot as hell on long summer highway trips. That too is more spread out.
I could be wrong but I also think those tires are rated for 75mph and maybe more.
I can end this debate for you real fast! Trailer tires, which will have an ST in front of the size, should always be inflated to the maximum psi indicated on the tire. ---. On a regular trailer tire you would inflate it to the max psi indicated on the tire because trailer tires are built with a thicker sidewall to handle more vertical load.
If a trailer tire is under inflated, because of the thicker sidewall it will generate excessive heat and that is what leads to failure.
Rusty is absolutely correct about the tire pressure. Most blowouts are caused because of under-inflation.......trailer tire are supposed to be run at max pressure. Not so with passenger car tires though.
Interesting, just a quick look it seams that the ST tires all give max inflation at 65 psi, where the others have much higher running pressures 95 -105 psi for example. So it makes sense.
My new 12in radials are load range D, and have a max pressure of 100psi. It seems crazy, but the manufacturer designed the tire to carry the load at 100psi so there isn't excessive flex. Flex builds heat wich is the downfall of all tires.
Here's the manufacturers website
You are just guessing and you guessed wrong. Follow the advice here.
2,000 miles or 2015 tires - and I checked my tire temps with the back of my and and my remote TPS. Did not lose any psi, look great, ran great. I will report when they fail, if ever. More likely that I will wear out the tread first.
BTW - just because folks in the business do stuff does not make it right, two of my local tire shops always grossly over-inflate my Jeep's tires far beyond the placard on the door pillar.
Fact is, you can run whatever psi you want... You paid for the tires. Use them how you like.
I, (and it seems like everyone else here) will stick with what the manufacturer's suggest.
My local tire shop over-inflates tires as well. I always let the pressure back out to what the door pillar states. But don't confuse tire shops with tire manufacturers. Manufacturers set the recommended pressures for wear, longevity, and safety.
I wonder why you even asked for advice here.
Now you are comparing apples and oranges... Are the tires on your JeeP the OEM stock size, stock brand and stock model of tire?? That sticker on your vehicle only is relative for the factory stock tires..
Tire manufacturers tell you to run ST tires at max inflation to achieve the maximum tire capacity rating. Since the industry runs axles and tires that are just enough to carry the weight of trailers (generally speaking) then it’s a pretty good idea to run them at the max inflation. This gives you an upside - which is less sidewall flex which reduces heat that is generated by the tire, but gives you a downside - which is less sidewall flex resulting in a stiffer ride.
Since you normally don’t ride in a trailer, the stiff ride doesn’t outweigh the benefit of the greater capacity and lower heat.
Tires on tow vehicles typically have higher capacity ratings than required for the vehicle (more safety margin) and you can run them at less than max inflation that still has sufficient capacity. The vehicle manufacturers’ recommended psi for the tires they choose for the car is a compromise that provides enough capacity and also gives you a comfortable ride. Yes, it does generate more heat than running them at max psi, but it is a trade-off. The space saver spare tires are usually smaller and you have to run them at much higher psi to get the same capacity. If you’ve ever had to drive on one, you can vouch for how crappy the ride becomes. Trailer tires are similar in size and capacity of the space saver spares.
It's unfortunate Goodyear chose to not offer their excellent US manufactured Endurance tire in the 13" size as those of us who have installed 14" and larger sizes on our travel trailers would arguably insist they're the current best in class, or certainly one of the best. Given this, my recommendation for an ST175/80 R13 would be the Carlisle HD which is available in both LR C & LR D.
I'm assuming one could get a 14" in a different ratio to match the 13" OD, right? I've still got to replace my pup's tires, and was considering new rims, too. I've got a few inches to spare, so I'm not worried too much about upsizing, but for others, it might be worth following your recommendation.
On a different note, any concerns with stepping up a load classification? I like the safety margin of going from a C to a D, and of course, definitely looking to get faster tires. My TV's can handle it.
A Carlisle HD ST175/80 R13 is 24.1" in diameter which is typical for that size tire. The smallest Goodyear Endurance, ST205/75 R14 is 26.1" in diameter, which is quite a difference. The Endurance certainly would be an upgrade if you had the wheel well clearance.