Trailer tire pressure is a critical topic for every trailer owner. Today, we’ll discuss several aspects concerning max air pressure, minimum air pressure, and everything in between. So, we’ve got a couple of great questions. One of the most popular questions is: What determines or who determines how much or how little air pressure I can put in my trailer tire? Well, you choose. You are the owner of the tire and the owner of the trailer, and you will determine how much air you put in it or how much air you don’t. It’s really up to you. Some people like to air down, and others prefer to air up. We’re going to cover that. Once you leave with the trailer and purchase it, it’s your baby. So, make sure you’ve done your homework, make sure you’ve done your research, and make sure you’re doing what’s correct.
When talking about max air pressure, the wheel is something else that determines air pressure. The wheel is limited to a certain amount of maximum air pressure. This wheel here is an 80 PSI maximum air pressure wheel. How do you know that? Many times, it’s stamped on the wheel. Suppose you have a wheel and cannot find that anywhere; you will have to try to figure out the manufacturer of that wheel. You may have to contact them or do an internet search to find out what wheel series this is. This here is an 8-lug wheel. I could bring another 8-lug wheel that looks identical but is rated for 110 PSI. But those two wheels, even though they look similar, are different. They’re going to have a different valve stem in them; they’re going to have a heavier PSI valve stem. They will also be made of a thicker material on the wheel itself. So, the wheel determines the maximum air pressure you can put in it.
What if you put a tire with below-max air pressure on the wheel? Then you have another conundrum. The tire is going to determine it. What if my tire had air pressure higher than the wheel? Then, the wheel determines it. So, that’s it. They have to match. You cannot go above the wheel if your tire is rated for more than the wheel. If your wheel is rated above the tire, then you can put the tire at what the tire recommends. You should focus on these things when determining the correct air pressure: look at the tire pressure and what the wheel is rated for.
There’s something else that would also determine the correct tire pressure: your data tag that the trailer manufacturer states. It could be different than what’s on the tire. It’s never going to be higher. If the manufacturer-recommended air pressure on the trailer is a higher PSI than the max air pressure on the tire, then it’s got the wrong tires or wheels on it, and you’ll need to take that up with your manufacturer. They may have put the wrong ones on it. I will show you the tire ID tag on the trailer, which will give you the recommended PSI.
Here, our tire and loading information tag should be on any new trailer. This trailer is running a 225/75R15 E-rated tire, and it says here 80 PSI for the maximum. If you were to go back and look at the tire, it would also say 80 PSI maximum. The wheel has an 80 PSI maximum. So, this trailer is not underrating the tire, and they’re not overrating it. The manufacturer states that they should run the tire at max air pressure, which will answer a couple more questions. Let’s jump back over here and look at our tire. But check this out: if you have this on your trailer, it has some good information. You also have this on your automobiles, where you’ll notice some differences.
Look at your automobile; often, the recommended tire pressure will be less than the maximum air pressure of the tire. This is because tire pressure can vary per vehicle depending on the tire setup. For example, if you have a 3/4-ton pickup, a 1/2-ton pickup, or a one-ton pickup, you’ll often run more PSI on the rear tires than you do on the front, to allow for the load in the bed or if you’re towing a trailer.
So, let’s jump back over here, look at this tire, and answer a few more questions. You notice here we have an empty trailer—there’s no type of equipment on here. It is ready for equipment or whatever you may load on it. And here comes the question we get from several people: “Can I air my tires down?” The short answer to that, in my opinion, is no. I’m sure This is where it will stir some of you all up. We’ll probably get some comments on that, but that’s fine—we probably won’t agree or get along. But I’m going to tell you my reason behind it, and you can do your research on that.
Technically, you could air the tire down on this unloaded trailer. The only reason you would want to do that is for a little more cushy, smoother ride because a trailer like this, pulling empty, will be bouncy. You have four of these tires at 80 PSI, the suspension is brand new, and this trailer—you’re going to know what’s back there going down the road. If you live in our area, our roads are horrible. We have a lot of traffic and cracks in the streets, and you’re just bumping up and down all the time. So yes, you could lower the air pressure out of this, giving you a smoother ride.
Tire manufacturers, for the most part, do not recommend that. There are some new ST tire manufacturers out there that do have an air-down rating. Charts are hard to find, but if you can find them, more power to you. Again, remember, it’s your decision. This is just my opinion and my decision. The problem with airing down is twofold. First, you could have abnormal wear on the tire. But the biggest thing is, if you’re pulling your trailer around all the time, there’s no reason to tow a trailer around unloaded. Trailers are made to be loaded. But I understand if you’re taking a piece of equipment somewhere, going to get material to drop off, or you’re a long-haul hotshotter, you’ll drop something off and have to head back unloaded. I get it. You could air down to give you a smoother ride.
Here’s the problem: How many of you will air back up, or do you remember to air back up once you get to your load or put a load on it? Most people aren’t. I know I wouldn’t. I would be the first to forget. So, I’m just going to deal with the bumps. Or, if I’m pulling a trailer around unloaded often, I will look at why I’m pulling a trailer around unloaded. I’ll put a load on it. Something else that could cause that bounce is a tire that’s not balanced.
So, my answer is: can I air down my trailer tire? I’m going to say no. And for the RV community, the travel trailer community, the cargo trailer community—guys that keep their equipment on—maybe this has some industrial equipment on it—you don’t want to air that down. You have to keep that at max PSI to get max weight capacity because that’s what you’re doing when you lower the PSI of that tire: you’re decreasing the max capacity of the load, the cargo, and the payload you can put on the trailer.
Here’s really what prompted this video. We were about 110 here last week, and we’re supposed to be in the 80s for the highs next week, with the upper 60s for the lows. Here’s the problem with that: when you go from 110 daytime highs down to 80 daytime highs, you’re going to do one thing: you’re going to lose air pressure in your tire. So, you’re going to have to start checking them. This time of the year, where we live, if you live up north where maybe you’ve already got some cool weather—hopefully you have some cool weather—you lose air pressure the colder it gets, just like the hotter the tire gets, you’ll build a little pressure. So, you need to be checking those tires. You need to check them every time you tow. And I know everybody will check your tire pressure and lug nuts every time you pull, right? Raise your hand if you’re going to do that. I doubt it. But you need to. I need to. We all need to.
So, my opinion: do not air down your tires. If it’s bumpy, deal with it. Try not to go unloaded—it is what it is because you won’t remember to air them up. Or, you’ll get loaded and say, “Man, I forgot.” I’m not going to have an air compressor available. If you have one of those little cheap plug-ins like the one I carry around with me in the truck that plugs into the cigarette lighter, it will probably take you four days to get these things aired back up. Yes, it will make it smoother, but it’s probably going to cost you some money, some headaches, and some grief.
So, what is the maximum air pressure of the tire, or what is the trailer manufacturer recommending? If you’re running a travel trailer or a cargo trailer, and it says 65 PSI on the trailer, and your tire is at 70 or 80 PSI max, run what the trailer says. There’s a reason behind that—they put that on there, that’s fine. But they will recommend max air pressure nine times out of ten in the trailer world. In many bigger tire stores, if you roll in with an ST tire and have it changed out, you say, Hey, will you put 10 less in there? They will probably tell you no; we will put the maximum air pressure in there. And then the other argument: well, once it gets heated up, will it build pressure? It’s going to build pressure. The tire has been engineered with that in mind; they’ve made an allowance to accommodate that. Then, when it cools back off the next night, you’ll still be at or close to your max air pressure. So, keep your tires aired up to what the manufacturer recommends, either on the tire, trailer, or both. But in the trailer world, most of them are going to match. It will say that if it’s 80, it will be 80. If it’s 110, it’s going to be 110.
We have tires that come in here all the time, which are 16-ply, 18-ply tires that are 110 PSI tires—some bigger than that—they’ll have 40 lbs in here. They look pretty good unloaded. They’re standing up; there’s no squish. If you’re to load a piece of equipment on there, they’re going to squish. What that’s also going to cause is improper heating of the tire and improper tire wear. It’s just going to cause you much heartache. It’s not that hard to go out and check your air pressure. I mean, get you one of these—they make some with little dials, as you can put in your glove box. You don’t have to buy an expensive one as long as it works. Buy you a cheap one; they usually have them on the counter at the parts store. You can use something like this as a remote if you’re scared about the tire blowing up or have a tire that’s hard to get to. We use this for our tractor and the inside valve stems—the only way you can reach them. It’s got a gauge built in. This is a little pricey; I’m probably not going to buy one of those, but buy this or something a little smaller to check your air pressure.
So, what determines air pressure? You determine air pressure. If you’re going to be on here and say, “Hey, I air down because that’s what I do, and my great-grandfather aired down his wagon wheels,” then go for it, brother—air down all day long, run 5 PSI in there if that’s what suits you. But make sure you’re okay with it. Ensure you can sleep at night and ensure everybody else on the roadway is safe. I’m just going to deal with the balance. I’m going to keep my 80 PSI in my tires. If it says 80, I’m going to keep 110 in there. If it says 110, I know that’s a lot, but that’s what’s recommended. That’s what the tire was engineered to do; that’s what the trailer was engineered to do—to haul so you can get your maximum load.
Imagine how much you’ve cut down your load capacity if you take an 80 PSI tire and put 50 PSI on it, whether on purpose or through neglect. Just figure out the math on that. If you’ve got half or a third air pressure, you’ve got a half-load capacity or a third load capacity. So, you could get yourself into a blowout. If you live in a hot state right now, there is rubber all up and down the roads. Most of that is not due to proper tire maintenance or proper loading; usually, I typically attribute it to improper inflation, worn-out tires, or cheap tires. Before you all guys beat me up on this being a cheap China-made tire, I picked this tire out specifically because it was the closest to this trailer, and I didn’t have to go to the tire bar.
Today, we’re talking about ST tires—specialty trailer tires. We’re not talking about LT, passenger car tires, or anything else. We’ll get you all stirred up on that on a different day. But today, we’re going to try to stay calm and talk about PSI. But tire pressure and lug nuts are super important. It will keep you going to where you’re going and not have a breakdown. If this tire blows out, what’s it going to tear up? It could tear your fender off, could tear up all your wiring, it could come off and tear up somebody’s car, and your insurance would have to cover it.
So, remember: who is responsible for proper tire pressure? I am. You are. Get you an air gauge and check it. After you check the tire pressure, check the lug nuts. We’ll see you next time.