Sorry I hit it too soon lol.  Ok I had a blowout on I 35 the other night.  My Trailer, an Elite 3H with 10ft SW is only a year and half old so tires are still practically brand new.  They had 10 ply Hancook on the trailer.  While I was in Discount Tire a man overheard my Convo with the Discount employee and said you better not put 10 ply back on or you will have more blowouts.   Fortunately they were out of 10 ply and so while waiting for the man to find more I posted on FB to my horse friend and literally everyone that responded, everyone said get 14 ply.   They were out of those too so I had to drive to Weatherford (horse country) to another DT they had a lot of them.  The man that helped me was so knowledgeable and agreed with the customer about the 14 ply.  THey only had 2 choices a cheap one I had never heard of, and Goodyear 14 ply so I went with the Goodyear and spent 1550.  OUCH.  

Oh and I called Longhorn Trailers and spoke to they guy that sold me the trailer and he said oh we always put 10 ply on your size trailer and have never had issues.  I still decided majority rules because most of the people that responded to my fb post were futurity, rodeo ropers etc.  lots of knowledge there. 

Here is the actual question.  WHat PSI should I put in? Discount Tires air compressor only goes to 90 so thats whats in them now.  I got a Wide range of answers there.  Some said 80 psi, some said keep at 110 psi.  some said go to 100 psi because when it heats up it will be at max psi.  

What do yall say?

I find it important to have them on my trailer.

Give us specific details 

If the question is are they expensive, the answer is yes.  We spent almost a grand reshoeing our trailer last summer.

14 ply or "G Rated" set at about 90lbs. I find if I put them to 110, as it says on the tires, the ride is too rough. Especially if you only have one horse in.

if they are ST tires, run them at what it calls for cold, otherwise, you risk more blowouts.  There is a great FB group that many knowledgeable people will answer too.  https://www.facebook.com/groups/trailersandtrucks

14 ply for darn sure, but cant tell you how much air/pressure, my hubby does all that for me

The tires they put on new trailers that are being sold are pretty much junk tires, they always use the 10 ply at most places not all but most, I always had the 14 ply for all my trailers, they are safer and last longer.

and always make sure they are putting NEW tires on .... we've caught dealerships trying to sell us tires that were never used, but up to 4 years old!!  We make sure we check the manufacturing date on all of them now.  

For air pressure, look on the side wall of the tire. It will tell you. 

How much weight are you carrying on your trailer axles. 

That is the first thing you need to know. 

Another factor not mentioned is the PSI limit for the rims.  I recently upgraded from 10s to 14s myself, but was not able to fill the tires up to the max PSI listed on the tires because that was greater than the max of the rims.  Not too much difference, but something to consider. 

I also investigated a lot of tire options and and was shocked at how many were not rated to (my) normal highway speeds.  I let my husband pick my presvious tires and come to find out they were only rated to 65...  no wonder I had 2 massive, rip the fender off blow outs in one single trip.  

Go by load range and not plys. 14 ply tires are rated 14 ply. They don't neccessarily have 14 plys. In fact, they almost certainly do not. I built tires for 18 years. For Goodyear. 

As for tire pressure, use close to what it recommends on the sidewalls. Like someone else said, be careful on the rim rating as well. But, if your rim rating is lower than your tire rating you have the wrong rims for your tires or vice versa. 

Heat is the enemy of your tire. That's why they tell you to add more air, less rolling resistance =less heat. Tires side by side in those small wheel wells build up a lot of heat. Just put your hand on the sidewall after highway hauling in hot weather and you will see. That's also why it's important to keep your wheel bearings well maintained. When you check the heat if the ceter is too hot to touch then get it serviced. Err on the side of caution with gooseneck trailers especially. Not every truck coming down the road can help you pull a GN out of the way. 

As a Goodyear retiree I get a good amount of discuout coupons every year. And they are sharable and I do share them. They are use them or lose them and they want us to share them. So if you need some Goodyear tires hit me up and if there's some codes left I'll send them on. It's usually 35% off plus they pay for mounting and balancing Alos usually includes a gift card. 

They recenly sent me an extra code for 45% off plus a $75 gift card. I put 4 Goodyear Wrangler Kevlars on my truck for $445 total. That's tax and the used tire disposal fee. When I get my $75 gift card it will have cost $370 for 4 new tires. 

Just out of curiosity. What exact goodyear tire model do you recommend for a horse trailer... 3 horse with an average living quarters, let say 10ft Short wall? 

Fully loaded I pulled around 15K lbs. I used load range E HT trailer tires. Naturally Goodyears. Kept the PSI at 75-80 lbs. As someone else noted, may of the gas stations air compressors won't do the job and the ones that do are hard to get to with a trailer. So I carried my air compressor with me. It wasn't a large unit but had a 120 PSI capacity. I carried my air wrnces with me too in the tack room. We halued almost 20K miles per year showing and tire and wheel problems happen. No matter how careful you may be. If I never had to get that stuff out then it's a good thing. 

Keeping a regular check on the air pressures will alert you to a problem. If 3 tires have 80 lbs and 1 has 65 you won't notive that by the eye test. But there's a reason that tire lost 15 lbs. Might as well find out at home than on the side of the highway. 

Run it at what the sidewall says. There's a reason they're supposed to be set to that. There is a difference in 14 ply tires - I have semi tires on mine that are rated for 75 mph and so many lbs based on my trailer. Check what your yours are rated for speed wise. You'd be surprised at how many are 14 ply and only rated for 65/70. Yes yes yes going over 75 in a horse trailer probably isn't in most peoples cards but if you haul a lot like I do (3000 miles+) in one trip, I did NOT want to be going 65 the whole time driving through Iowa lol. 

WTH is a semi tire?

Yes!  THIS^^^^.  Recently a friend had a blow out in Claremore and had to buy a tire -- she paid for a new Good year -- which shredded into pieces about a week later - - fortunately, only a few miles from her home. Her hometown tireman came to her rescue and when he checked the tire in the computer it was a 10 YEAR OLD TIRE sold to her as new.  So - BE SURE to verify age of tires when you purchase!!!!

Problaby referring to a rim size of 17.5 or 19.5.