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[RWAGNER]

I have had several different opinions on the correct tire pressures I should be running in my boat trailer tires. I have a single axle trailer towing a 18 ft. nitro with a 150 merc. The tires on there are the ST trailer tires rated at 50 psi. I recently bought new tires from Jim's south and they only put 35 psi and I am pretty sure they need more than that. I appreciate all opinions!

[Ron Fogelson]

What ever PSI is printed on the tire use that.

[BigDBasser]

What ever PSI is printed on the tire use that.

That is good information.  Most tire people don't really know much about trailer tires.  I even had a national tire chain try to tell me that you don't need to balance trailer tires.  I had another tell me that you can't put radial tires on trailers.

I'll say this, if you keep the tire pressure correct according to the rating on the tire and balance them, they will last a lot longer.  Radial tires will last longer on a tandem trailer than regular ply tires.

[bass11.11]

I run a 17.6 Skeeter with a 135 Mariner and a "ton" a crap in it on a single axle trailer.  My rig was bought new in 1995 and I'm on my second set of tires.  I have had very good luck with the Goodyear Marathon with pressure at 45-47lbs.  My tires wear even with no scallopping.  My trailer is a Easyloader.

[coldfront]

What ever PSI is printed on the tire use that.

I replaced my tires on my trailer last year...was surprised to learn that I had incorrectly assumed the tires I 'had' were rated for highway speeds (they weren't...)

double check not only air pressure requirements...but speed ratings...

I think I was fortunate not to have a blow out towing my trailer...as I'd routinely exceed 70mph...


more than a few things to think about here...

[hpdi200]

What ever PSI is printed on the tire use that.

He is right, I got a tandem trailer, my tires say 50 psi. I run that in mine.

[Large_ Mouth]

Also remember that on the side of your tire it says psi COLD tire pressure.make sure you check your tire pressure before you get on the road not after you have been driving for 2 hours and then check them that will give you a false pressure reading due to the heating of the air in the tire thus giving you a higher pressure reading

[RWAGNER]

Yeah i pretty much agree with all of ya'll. It just threw me for a loop when the tire dealership only put 35 psi in them . Thanks fellas! Lots of good info

[StopShort]

PSI on the side of the tire is the max tire pressure. If you inflate your tires to max pressure you will exceed the rating once the tire becomes hot.

I have always ran the same pressure that i do in my truck tires...35 psi.

[Ron Fogelson]

A tire will only over heat enough to significantly change the air pressure if there is something wrong with the tire, the bearings on the axle, over loading the vehicle/trailer or letting it become under inflated causing the side walls to compress/flex deeper and more often than the design the tire was intended to.

Vehicles manufacturers have been under inflating tires to help provide and smoother ride for the customer.  Does anyone remember the issue with FORD a few years back with all the roll over’s caused by blowouts    As a 21 year AF vehicle operator it is standard to have no more or no less than a 10% difference in the tire pressure from the recommended max.  Ask any truck driver the fastest way to blow a tire is to over load it with cargo beyond its rating or fail to keep an eye on them letting them go low and be under inflated.

[brobutch]

I have an 18.6 boat with 150 vmax. 14 in Goodyear Marathon tires,  single axle and I run 50lbs of air. Trailer rides better and tires last longer.

[screwballl]

PSI on the side of the tire is the max tire pressure. If you inflate your tires to max pressure you will exceed the rating once the tire becomes hot.

I have always ran the same pressure that i do in my truck tires...35 psi.

Actually that is false.
As mentioned, the 10% leeway is typically suggested for radials, and for bias ply trailer tires, it should be about 5%.

1) The cold PSI rating is designed to take the tire heating up into account, which is why most tires of any kind typically have a "max pressure" rating. It is also based on the weight rating. So if you run your trailer (not car/truck) tires listed at 50 psi at 35 psi cold, you reduce its load carrying capacity by a lot.
2) Trailer tires and car tires are different animals because of their construction. Trailer tires (ST) need to be run close to its pressure rating, where as car tires are setup with multiple ratings, Max pressure, and a recommended pressure. A car may have max pressure 40 psi with vehicle specific recommended pressure of 35 psi, versus a trailer's max is the same as it recommended pressure, which is why it is listed as "tire pressure rating", and not "max and recommended pressure".

Example: Say at 50 psi the load range is 1000 lbs (per tire), the same tire at 35 psi could only handle 600 lbs (each). So if your boat and trailer is 1500 lbs loaded, you are safe at 50 psi (1000 x 2 tires = 2000 lb), but not safe at 35 psi (600 x 2 = 1200 lbs). The same goes for excessive pressure: at 60 psi, the rating would also drop exponentially to around the same rating (1200 lbs). The main difference is that a low pressure tire typically just goes flat where it is easier to safely pull to the shoulder or safe spot to change it, whereas over pressurized tire can actually explode sending the trailer all over the place, and more likely causing an accident or you losing control.
The only time it may be safe to use it at lower pressure is when there is a much lower weight load. If your boat and trailer is only 1000 lbs loaded, then the tires at 35 psi (1200 lbs) would still be safe enough to travel on, although the tires would still not wear properly and need to be replaced prematurely.

3) My popup camper has a bias-ply Class C tire rated at 80 psi cold (the spare). If you run the tire more than 5 psi above or below that pressure, the tire blows each and every time within 20-30 minutes. Same for the Class B tires rated at 55 psi. I have had to replace several tires over the past year because of them running below the recommended psi (one was done as an experiment which ?succeeded? as I expected). 

4) Radials (for trailers) give you a bit more leeway but it is still only suggested to go at most 5 psi below or at most 3 psi above the recommended rating.

ALWAYS (try to) run TRAILER tires within 2-3 psi (cold) of the rating on the side of the tire. No exceptions.

[Lawguy513]

I think Dear Leader (President Obama) had already weighed in on the issue.  He wants you to fill up your tires to increase fuel efficentcy.  I guess we had better do as he says...

[Ron Fogelson]

I think Dear Leader (President Obama) had already weighed in on the issue.  He wants you to fill up your tires to increase fuel efficentcy.  I guess we had better do as he says...

I thought he was going to take all the air pressure from my 4 tires so it could be redistributed to 8 folks who have no pressure as I obviously had the means to get my own in the 1st place and could replenish it over time.                     

[Lawguy513]

I thought he was going to take all the air pressure from my 4 tires so it could be redistributed to 8 folks who have no pressure as I obviously had the means to get my own in the 1st place and could replenish it over time.                     

He has enough hot air that he doesn't need to take any from us!  But if air was money, then look out brother!

[Grab my Bass]

Just got a new set of trailer tires for my Tracker trailer, 2005 original tires, shredded one on the way back from a trip with Bass 11.11. I use the nitrogen instead of air, keeps tires cooler, and they never lose pressure.