What psi do you run in your trailer tires?

BigClay

BigClay

Knower of useless ZJ things
Joined
Sep 24, 2008
Location
Winston-Salem
I curious if I am running enough air pressure in my trailer tires. The tires are bias ST225/75D15. The trailer is tandum axle, 18ft long with a 7k pound rating. Max pressure on the tire says 65, so I am wondering if youi guys run max pressure in it all the time.
 
I run max pressure, but I'm also running max weight. If the loaded weight was substantially less than the rated tire capacity, I'd be fine with dropping the pressure down some. It might ride nicer that way, too.
 
The tires on my 16ft Kaufman standard car trailer state 35psi max. That is what I put in them.
 
I always go recommended max on every tire I've ever owned except when I'm trying to play supertruck hauling something I shouldn't. Then I go 5 pounds over and air back down afterwards. The fact is you have less road contact with recommended max than with any less which equals better fuel economy and better sidewall tire wear. Plus how do you go wrong with "factory recommended"?
Of course this only applies if you have "recommended" rim size to match as well. Anything else, I guess the ole chalk trick is recommended.
 
I run 5psi under max pressure to make up for when the tires are still "cold". But I'll run them up to max if I'm checking/adding air after I've already been towing and allowed the tires/air pressure to reach it's warm temp.
 
Usually 5 under, unless it really cold outside. Road temps will bring it up. If really hot outside I might go 7 under.
 
upnover said:
Usually 5 under, unless it really cold outside. Road temps will bring it up. If really hot outside I might go 7 under.
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Don't change the cold psi based on the ambient air temperature. Pressure is meant to be measured when the tire is cold. 2psi isn't going to hurt anything, but I don't want anybody thinking they need to run lower cold psi on hot days or that they should let air out of the tire once it's been running a while and warmed up.

That said, I usually do add or remove air as the seasons change to keep them at 80.
 
I've ran a loaded trailer at 5 under to begin with, and first stop at 100 miles or so, and the PSI would be10-12 over the cold PSI max.Travel temp being mid to upper 90's. So, I have wondered why there is not a Max Hot rating on tires. I've don't this just to be on the safe side. I have a Hudson trailer with Dexter axles, and the Mobile home type tire and wheels(but I do use DOT approved trailer tires). I am thinking the larger trailers, with taller tires may not build as much pressure hot, due to their size. but I know my smallish tires sure will.
 
upnover said:
I've ran a loaded trailer at 5 under to begin with, and first stop at 100 miles or so, and the PSI would be10-12 over the cold PSI max.Travel temp being mid to upper 90's. So, I have wondered why there is not a Max Hot rating on tires. I've don't this just to be on the safe side. I have a Hudson trailer with Dexter axles, and the Mobile home type tire and wheels(but I do use DOT approved trailer tires). I am thinking the larger trailers, with taller tires may not build as much pressure hot, due to their size. but I know my smallish tires sure will.
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That's my point - max hot doesn't matter. The tire is designed to carry the max specified load under all driving conditions if it's inflated to the max rated psi when the tire is cold.

You might find that if you inflate the tire to its max pressure that it doesn't heat up as much during travel and thus actually has a lower hot pressure reading. I know I had a similar situation in the past with a tire that was underinflated, got hot, and had a higher hot psi than its buddies. I did a quick guesstimate about how much more air it needed, added a few pounds to it, and it actually cooled off and the pressure dropped after an hour or so, despite me having added air to the tire.

If I put 80psi in the tires before we leave the house and I check them a few hours down the road, they might have 85 or 90psi in them at that point. But on those "en route" checks, all I'm interested in knowing is that the pressure on all the tires is more or less the same -- that one tire isn't significantly higher or lower than its buddies. If I have a tire that's hugely different, then something is wrong with it. Maybe it picked up a nail and is slowly leaking, maybe it's just starting to come apart, who knows. But at least then I have the option of swapping it out before it comes apart and does collateral damage (including overloading/overheating the tire next to it).
 
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Hmmm....nitrogen in trailer tires? :lol: Probably wouldn't be a bad idea in all honesty.
 
What is the benefit of nitrogen?
 
Less pressure change due to heat.
 
What he said. It's an inert gas that is basically unaffected by temperature change. That's why so many newer vehicles with TPMS setups recommend nitrogen in the tires.
 
Croatan_Kid said:
What he said. It's an inert gas that is basically unaffected by temperature change. That's why so many newer vehicles with TPMS setups recommend nitrogen in the tires.
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Actually, running dry nitrogen devoid of the oxygen and moisture from ambient air keeps the TPMS sensors alive. Moisture+oxygen+heat = corrosion. It can also slow internal breakdown of the rubber in the tires.

Unless you are racing or have sensors in your wheels, don't waste the money on nitrogen in your tires. Remember, air is already 78% N2!
 
I'd venture to guess being void of moisture is also what helps it be unaffected by temperature changes.
 
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