# Proper trailer tire pressure ?



## Andy Taylor

I read that trailer tires should always be inflated to the max. cold pressure on the tire? Is that accurate?

If so, what about when the load is very light, and you are experiencing a rough, bouncy ride?

Thanks.


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## KMixson

In my line of work I have dealt with vehicle manufactures and tire manufactures. Depending on who you talk to the answer is different. The vehicle manufacture tells you to use the pressure stated in the cars manual and the tire manufacture tells you use the pressure stated on the side of the tire. I think if you put them in the same room they would fight. I can see both point of views but there is no clear cut answer. Myself, I tend to go with the tire manufacture view. You can get a smoother ride with a little less pressure but you need to keep an eye on tire wear and adjust accordingly. A trailer tire with less air also has a little more rolling resistance and therefore will work your bearings a little harder.


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## lckstckn2smknbrls

I use max tire pressure. I run load range C tires at 90psi on my 4x8 utility trailer, I have no issues when pulling the trailer empty.


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## earl60446

I adjust the tire pressure for the load and what kind of springs I have on the trailer. Not good to have a trailer bouncing around going down a highway. Short trailers are worse for this. Too much or too little pressure will also cause uneven wear on tires.
Tim


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## Keystone

earl60446 said:


> I adjust the tire pressure for the load and what kind of springs I have on the trailer. Not good to have a trailer bouncing around going down a highway. Short trailers are worse for this. Too much or too little pressure will also cause uneven wear on tires.
> Tim




Right along the same lines as Tim. Keep in mind that the tires are stamped with the MAX air pressure. I pulled a small trailer behind my Harley. If I inflated the tires to the 50 psi max the trailer bounced all over the place even when fully loaded. Not safe. Rear tires on my Trike are stamped 36 psi. Run them at that and the rear of the trike will hop around something fierce.


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## Andy Taylor

Thanks guys. The reason I asked is because I modified a 5' X 8' utility trailer to haul 4 kayaks. All 4 kayaks and spare tire weighs only 250 lbs. The tires are 4.80 X12.


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## lckstckn2smknbrls

Andy Taylor said:


> Thanks guys. The reason I asked is because I modified a 5' X 8' utility trailer to haul 4 kayaks. All 4 kayaks and spare tire weighs only 250 lbs. The tires are 4.80 X12.


Does that 250 lbs include the weight of the trailer?


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## jadatis

Registered to this forum to give you an answer.

Will copy text I saved from other forum, so dont have to write it again, meanth for cars/motorhomes, so can be a little of the question here.
But in next posts I can be more specific. But its true that for verry low loads a lower pressure gives enaugh reserve still.
And even if you have 80% of load realy on tire then the load the pressure is calculated for for 99m/h, still no bumping and even side to side surface on the ground. So there is a range in the pressure in wich tire is save and comfortable ( so screws wont turn loose by bumping)
Will give a link to my public map of one-drive, to start with, that belongs to my hotmail.com adress with same username as in this forum, with lots of tire-pressure maps, also in English. Also that for trailers.
https://onedrive.live.com/?cid=A526E0EEE092E6DC&id=A526E0EEE092E6DC!128

Here the copy.

Registered to this forum to react to this topic, found with google.
Live in Holland ( Europe) and once got hold of the formula for calculating pressure for a load and went running with it. Now call myself tire-pressure specialist. Got much wiser about it and maximum load of tires in the years.
So will not introduce myself in a seperate topic, because I dont own a car on this forum, only react on tire-pressure related questions.

Tirepressure advice is all about load on tire and speed ( and sometimes about alighnment - camber angle).

So if you can give details of car and tires , I can calculate an advice pressure with some reserve for things like, pressure-loss in time, unequall loading R/L, incidental extra load, misreadings of pressure scales,and misyudging of weight, etc.

This is from tires next and can be read from sidewall:
Maximum load or loadindex.
Kind of tire to determine the AT-pressure/pressure needed for the maximum load up to maximum speed of tire, or if lower 160km/99m/h/reference-pressure, wich is not the maximum pressure of tire.
Maximum speed of tire, most given as letter ( Q=160km/99m/h,N=140km/86m/h fi)
If you have offroad or tires looking like that , with large profile blocs that cover a part of sidewall, also mention, they are allowed lesser deflection then a normal road tire, then the tire maker used to determine the maximum load (to my conclusion the case for the Bridgestone tires on Ford Explorer in the Ford/Firestone affaire).
If you cant find all of it give sises of tire and Loadkind, then I will google for it.

From car next and mostly can be found on same plate as the original pressure advices:
GAWR and GVWR ( Gross Axle/Vehicle Weight Rating)
But best would be to determine the real weights in your use on seperate tires or estimate it as acurate as possible, by weighing per wheel(pair) or axle.
Maximum speed , you dont go over for even a minute in your use, eventually different for different situations, for instance when towing or fully loaded.This apart from trafic regulations, if you drive faster then allowed give that speed. Nature punnisches with tire-failure, police only with a penalty.
Give all that and I will calculate and give a picture of one of my filled in spreadsheets in my answer.
If other then original tires, indead as is already answered other advice is needed, a stiffer tire ( fi C-load instead of P-tire) needs a higher pressure for the same load, or the other way around, has lower loadcapacity for the same pressure.

Greatings from a Dutch pigheaded self-declared tire-pressure-specialist.


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## nowgrn4

I run the max cold as stated on the sidewall. The flexing of the sidewall of an under-inflated tire generates excessive heat at highway speeds. Not good.


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## Andy Taylor

lckstckn2smknbrls said:


> Andy Taylor said:
> 
> 
> 
> Thanks guys. The reason I asked is because I modified a 4' X 8' utility trailer to haul 4 kayaks. All 4 kayaks and spare tire weighs only 250 lbs. The tires are 4.80 X12.
> 
> 
> 
> Does that 250 lbs include the weight of the trailer?
Click to expand...


No. The 250 lbs. is the weight of the 4 kayaks and spare tire. The trailer is in the link below. GVWR is 1,980 lbs. When I add in the weight of the wood, etc. the trailer is probably about 350 lbs. empty, plus the 4 kayaks would make it about 600 lbs. 


https://www.farmandfleet.com/products/669952-teske-mfg-no-floor-trailer.html


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## Insanity

I've always ajusted the pressure to the load. Even changed in trip before. Like when I use a wash board gravel road il deflate a lot of the air. Then air up again for the high way. 
I have a 6x12 utility trailer I use to pull hay and a zero turn mostly. I'm running used car tires on it because there wider and have a softer ride. Il over inflate until they don't pucker on the bottom when hauling hay. And run about 5 to 10 pounds less then the max when hauling say my mower. 
If the side wall is puckered out to much on the bottom you can feel the heat in the tire with your hand.


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