How often does everyone replace their trailer tires? I'm talking about ones that have good tread and no dry rot.

I wouldn't. LOL I have a couple that have slight cracking and I need to stop procrastinating and order new ones. I don't replace just to replace though. Maybe I'm the minority. If they are fine, I keep them going.

When the tred shows they need replacing.  We run 14-ply on our trailers so they last a pretty long while.  I don’t remember the last time we replaced one that wasn’t a case of a blowout or something like that.

Edited to add - never had a blowout on the horse trailer/livestock trailer.  Knock on wood now.  The tires we’ve replaced have been on our flatbeds and dump trailers.  

On our livestock trailers I agree with the below poster - if I had a blowout I felt was tire wear related I’d probably go ahead and replace them all on a livestock trailer.

On my current trailer I replaced them the first time when they started blowing out. One blew and then 2 others within 2 weeks. They were around 5 years old. I repalced them all last year as well since I had flat spots on 2 from locking the brakes with someone else's truck. I just replaced them all and went with 14 ply tires this time. If they have good tread and no dry rot leave them alone. I usually just wait until they start blowing out and I've come to find over the years once one blows out, the rest will follow shortly. Unless you haul hard they should last at least 5 years or more 

These tires have been on the trailer since I purchased it, almost 5 years ago. If I am reading the numbers on the side wall correctly, I think they were manufactured in 2007. I do haul almost every week but normally it averages about 80 miles round trip. However, I plan to go to a weekend series about 3 hours away, 2 or 3 times.

I usually replace every 5 or 6 years depending on use etc.  The LQ trailer is either in a barn or has wheel covers on & on boards, so that definitely extends their life.  I don't wait until they show cracking etc - don't like replacing fenders when they blow.

My hubbs a little excessive on safety issues with me and the trailer. I run Michelin XPS, which are very, very expensive but very, very good. We outfitted my first trailer with them after going through way too many blowouts and babies (bubbles on tire) and that set is still in use from 2010 with the new owner. My new trailer got outfitted with XPS also and I'm 2 years in on them. We will check tread for uneven wear but as long as they wear even they should be good for the legal life of a tire, which is 10 years. 

A big thing to take notice of is when the tires were manufactured.  Just because they haven't been on a vehicle yet, if the date on them is 2 or 3 years ago, that much life has been taken from them.  I had a jerk try to sell me "new" tires that were 4 years old!!  No thanks, I'm paying for NEW & I want new.

We tend to replace when the first one goes flat or blows out. I've got my trailer on a "schedule" where we replace them two at a time instead of all 4 at once, and I think my husband's trailer is on a similar "schedule." We tend to get several years out of them on his LQ trailer and the biggest part of 2-2.5 years out of tires on my stock combo, which goes down the road WAY more often. His trailer tires may not need replaced until 2020 because it's not likely to go on very many trips this year while I'm pregnant and he is the only one competing.

I replace every 5 years. meaning after the tires are 5years old. Be sure you get new tires as one previous poster mentioned.  I love my trailer guy and he looks at them every inspection, every year. Its not worth the blow out to me. Blow outs do damage to the trailer. And i'd rather just get new tires then new tires AND have my trailer repaired. Plus it's EXTREAMELY stressful to be in the middle of nowhere changing a flat tire wondering if you're gunna make your run number. ( I often travel alone). Been there, done that, no thanks.

My 02 F-350 dually and my trailer run the same tires. 235/85-16R Firestones and are all 2009 manufacture date.  My truck and trailer never sit outside.  I no problem running them another 5 years.   Never Ever run a trailer tire on a trailer unless it is a 14 ply. ST or trailer tires are just junk.  Run a LT or light truck tire as the quality of construction is much better.

Public service announcment 

everything said by this poster after "my '02 Ford Dually" is wrong. 

Just to update: I took my trailer to my tire guy. The tires are from 2012 (on the trailer when we bought it in 2014) and in perfect condition other then a flat spot from locking the brakes up one time. He recommends replacing due to age.

I have decided to replace with a ST 12 ply tire (currently LT 10 ply). I was planning to go away to a weekend race in a few weeks, 3 hours away, and don't want to risk being on the side of the road. I think if I was only going to be local I would hold off for a short while.

Agreed. When I get new ones I'm going to make sure they are no older then 2018. Preferably 2019.

Tell me what is wrong on my statement. 

Would you buy any new truck and except the tires if the dealer told you they are unsafe in 4 years. 

I don't go by age of the tires, I wait until they NEED to be replaced (blowout, won't hold air, weather cracks, going bald, etc).

My cousin got a brand new mobile grooming trailer and a few months later was talking about already needing new tires. I commented that she shouldn't be needing new tires so soon unless she's hauling it across the whole state every single day. She said the tire guy told her they need to be replaced every six months. I told her of course he said that, he's the one selling the tires

I prefer not to wait until I start having blowouts. No way I want to be stuck on the interstate with my horse in tow when it is something I could have prevented due to old tires.