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old skool malibu

Boatmate 18" tire pressure?

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old skool malibu

Reading the sticker in the trailer it looks like Boatmate is suggesting 50 psi for the Nexen 18" tires which is the max PSI of the tire. I asked my dealer and he thought 32 psi was the norm. So TMC what psi should I be running in these tires for my 2013 boatmate and VTX?

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thtrog

I run 50 psi cold, torque the wheels to 115.

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ToeCutter

I was startled to learn my tyres were meant to be at 65psi after a year of running them at 35. My tow vehicle performance improved measurably once I inflated the trailer to the correct pressure.

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Nitrousbird

I have my 18's @ 50psi cold. I could get away with less (I'm well under the max load rating) but better safe than sorry...plus you get better mileage with less rolling resistance.

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BlastRlxi

I would think that keeping the tires at the recommended pressure (50 PSI) would help in preventing flat spots during storage as well.

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SmoothWaterMan

Always verify and inflate to the max pressure stated on the sidewall, as others have stated. Single axle trailers will run a higher pressure than tandem's, and different wheels vary quite a bit. We see everything from 45 to 80 psi depending on wheels.

As always, inflate when cold.

Peter

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TheKiwi

LIke oldjeep said, you need to run the max psi rating to take full advantage of the load rating. Heavy load tires typically run at 50psi, lower rated tires usually call for 45ish.

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Kalamazoo

so...with the boat on trailer you fill all four tires to 50psi. the spare, which has no load, also is filled to 50psi. if you then put the spare in place of one of the other wheels, will it's pressure now be greater than 50psi due to the load it's carrying? hmmmm...

Edited by Kalamazoo

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Dare2goBare

I have the same ties and I run with 50 psi as per the Boatmate sticker. Spare to, I don't think

you'll find a big difference if you were to put the spare on after if any, especially with a tandem.

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TheKiwi

No. There will be a variation of a few psi but the load does not determine what psi the tire can hold.

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oldjeep

so...with the boat on trailer you fill all four tires to 50psi. the spare, which has no load, also is filled to 50psi. if you then put the spare in place of one of the other wheels, will it's pressure now be greater than 50psi due to the load it's carrying? hmmmm...

Huh?

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Kalamazoo

Huh?

If a spare is filled to 50 under no load, then put on trailer and carrying (lots of) weight will the psi increase significantly.

Sent from my iPhone using Tapatalk

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TheKiwi

If a spare is filled to 50 under no load, then put on trailer and carrying (lots of) weight will the psi increase significantly.

Sent from my iPhone using Tapatalk

No. There will be a variation of a few psi but the load does not determine what psi the tire can hold.

Edited by TheKiwi

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oldjeep

If a spare is filled to 50 under no load, then put on trailer and carrying (lots of) weight will the psi increase significantly.

Sent from my iPhone using Tapatalk

Uh - no. A demo

https://www.youtube.com/watch?v=wOHSJ7zUBIA

pV=nrT, which means pressure times volume is equal to the amount of gas times a constant times temperature. No matter the amount of weight, the volume will always be the same, as will the amount of air in the tire, r is constant, and the temperature is the same, therefore pressure remains the same. (Oddly enough the ideal gas law is what my daughters 10th grade science class is currently studying)

http://en.wikipedia.org/wiki/Ideal_gas_law

Edited by oldjeep

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pook77

Prolly shouldn't start your lugs with the drill like that. Just begging for a crossed thread. Finish em with a torque wrench.

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oldjeep

Prolly shouldn't start your lugs with the drill like that. Just begging for a crossed thread. Finish em with a torque wrench.

I agree - BTW that is a random u-tube video not me ;)

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Kalamazoo

Does a compressed tire have the same "V"?

Sent from my iPhone using Tapatalk

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nyryan2001

pV=nrT, which means pressure times volume is equal to the amount of gas times a constant times temperature. No matter the amount of weight, the volume will always be the same, as will the amount of air in the tire, r is constant, and the temperature is the same, therefore pressure remains the same.

^^ close but not accurate. The temps in the tires certainly change, drastically.... and the pressure goes up as the temps go up. folks doing 50 PSI cold = approx 55 PSI after a short drive down the highway.....unless you have nitrogen in your tires that expands/contracts much less than regular air. Also the volume certainly changes every bump you hit... the tire stretches and compresses.... that compression, even though small, over and over again is largely what causes the tires to get hotter. The action of squeezing air makes heat.

my boat is just under 9000lbs with trailer... 50PSI cold all around and I still get a little bulge on the front tire. Ive see my 50PSI cold go as high as 57PSI on 110deg day, 15-20 mins at 70mph.

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oldjeep

Does a compressed tire have the same "V"?

Sent from my iPhone using Tapatalk

If you were actually able to compress the tire in such a way that its volume was reduced. If you are at the rated pressure and load of the tire then that (should not) be possible. More likely what would happen is that enough pressure applied to the tire without restricting movement/stretch in any other direction would result in blowing it off the rim.

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oldjeep

^^ close but not accurate. The temps in the tires certainly change, drastically.... and the pressure goes up as the temps go up. folks doing 50 PSI cold = approx 55 PSI after a short drive down the highway.....unless you have nitrogen in your tires that expands/contracts much less than regular air. Also the volume certainly changes every bump you hit... the tire stretches and compresses.... that compression, even though small, over and over again is largely what causes the tires to get hotter. The action of squeezing air makes heat.

my boat is just under 9000lbs with trailer... 50PSI cold all around and I still get a little bulge on the front tire. Ive see my 50PSI cold go as high as 57PSI on 110deg day, 15-20 mins at 70mph.

Certainly, but that is why they specify cold PSI. We were only discussing load vs PSI

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Cory

Uh - no. A demo

https://www.youtube.com/watch?v=wOHSJ7zUBIA

pV=nrT, which means pressure times volume is equal to the amount of gas times a constant times temperature. No matter the amount of weight, the volume will always be the same, as will the amount of air in the tire, r is constant, and the temperature is the same, therefore pressure remains the same. (Oddly enough the ideal gas law is what my daughters 10th grade science class is currently studying)

http://en.wikipedia.org/wiki/Ideal_gas_law

You decided to get all scientific here. So, when you put the tire on the trailer and load it up with a boat, this causes a portion of the tire to flatten on the ground. This will certainly change the "V" in PV=nrT as the tire flattens and the rubber flexes. T is always changing. I would expect to see P change. How much? I have no idea. Common senses would suggest that if you stacked several tons of lead into the boat while on the trailer, eventually those tires will burst like a squeezed balloon. My instincts are telling me that internal tire pressure does increase with trailer load, but that is a mere (educated???) guess.

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Kalamazoo

who's got Bernoulli's number? he'd know...

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oldjeep

You decided to get all scientific here. So, when you put the tire on the trailer and load it up with a boat, this causes a portion of the tire to flatten on the ground. This will certainly change the "V" in PV=nrT as the tire flattens and the rubber flexes. T is always changing. I would expect to see P change. How much? I have no idea. Common senses would suggest that if you stacked several tons of lead into the boat while on the trailer, eventually those tires will burst like a squeezed balloon. My instincts are telling me that internal tire pressure does increase with trailer load, but that is a mere (educated???) guess.

Without getting scientific, just try it out. Jack up a tire off the ground and measure the pressure, then set it down and measure the pressure. That is what the video is showing - with no science at all;)

For a practical example of your tire flattening, drop the tongue of your trailer - look at how "flat" the front tires look (assuming tandem trailer) and then measure the pressure - yup still 50psi if that is what you started with. Now this is because you are not really altering the volume, just moving around where it is. If you managed to stick enough weight on there to crush the tire and not have it blow off the rim then sure your pressure will go up - you would have to be loading the tire beyond design limits for this to happen.

Edited by oldjeep

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oldjeep

And I'm not trying to be argumentative - its science ;) And like I said, my 10th grader was just asking for an explanation of ideal gas law a couple days ago - thanks to this thread I've got a more practical example.

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