Returning from teardrop trailer camping last spring, along a rural gravel road, in the passenger side mirror I notice either smoke or fine water spray off the road from rain that morning. Still trying to reason-out smoke vs spray, next glance in the mirror I observe my trailer tire, off its wheel, rolling onto the road shoulder and away into a farm field.

All a bit shocking, heh. Fortunately I was within a half-hour of home at that point, and at least I had a spare tire assembly with me. It was a bit fiddly to switch out the trailer wheels using the car’s jack but the planks I keep stowed for levelling came to the rescue. (Side note: you may want to trial the wheel change manoeuvre before you actually need to do it! And while you’re at it, check that your spare actually does fit your teardrop trailer’s wheel hub.)

Premature Tire Failure?

Once safely home, I unpacked the teardrop, poured a beer, then began trying to unpack what had happened and why. The end result, as you see in the photo, was dramatic but even just determining “what” happened was unclear. Was it an actual “blow-out” or a flat that ran so long the tire eventually degraded and separated?

Exploring the “why” was even more perplexing. It’s not that the tires were old (more on that below). And since I keep a teardrop road trip journal I knew the they were a bit shy of 9,000km, which wasn’t a whole lot of mileage. Over the days that followed I came up with several theories for what seemed to be premature tire failure and did some research to develop strategies to avoid a recurrence. I’m sharing the long story with you fellow teardroppers in hopes you never look in the mirror to see your trailer tire rolling away.

Never a Single Cause

Pretty much my only binge watch is a YouTube channel called Mentour Pilot. An airline pilot with extensive experience, he analyzes commercial aviation accidents and incidents in a way which is consistently professional, thorough and thoughtful. He refers to the “swiss cheese” model to illustrate how it is when several holes line up—some may be large while others small—that things go wrong. Even in accidents where there appears to be an obvious cause (e.g., a missile strike, or a hitherto unknown control system augmentation) there are always multiple factors.

While the “primary causal factor” for the tire separation (i.e., blow-out or flat or something else) is unknown, I speculated on a variety of “contributing factors”, some more likely than others:

• When not in use, my teardrop trailer was parked at home in considerable sun exposure especially on the right-hand side. It does have a cover but only for the trailer body.
• During off-season storage (which here in Canada is half the year!), trailer wheels remained under load, on the ground and never rotated, and were exposed to the elements.
• The final road trip of the season prior to tire separation included an entire half-day of particularly rough gravel road driving, which would have been an extended period of sidewall stress and thus heat; furthermore, most of my teardrop outings include some rough road travel.
• Most single-lane roads, particularly gravel and tar+chip, camber off at the edges so perhaps the right-hand side tire gets more wear-and-tear.
• Tire inflation is something I do check before every road trip but while inadvertent over- or under-inflation is a slim possibility if I misread the gauge it would only be by a small margin.

As it happens, the camping I was returning from was a gathering of the Tearjerkers online forum and I had the pleasure to hang out with a guy I first ran into a couple years prior (see his Super Shelter setup on my Cool Teardrops page). Ironically one of the topics we spent a fair bit of time gabbing about was tires. His mechanical intuition is better honed than mine and, in email exchanges following the tire failure, he didn’t think something like road camber for example was much of a factor if at all.

My teardrop friend Dave also had a simple reason for many of the trailer tire failures we see at the side of the road: spinning time bombs. That’s what he called the crappy tires that many small trailers come equipped with. No surprise then that, while he and I have essentially the same little 4×8 “Silver Bullet” teardrop from the same builder, he got his with larger wheels and recently upgraded to beefier tires.

Do Tires Have a Best-Before Date?

Sort of, though perhaps more of an advisory than expiry. One of several things I learned from Dave was that every road-legal tire will have a date code, usually shown within a squared oval (though sometimes as the final 4 digits of the DOT number) on the sidewall, which specifies the year (second pair of digits) and week # (first pair of digits) it was manufactured.

The date code on my blown tire was 2721, indicating it was manufactured the 27^th week of 2021. So just coming up on 3 years, it’s not that it aged-out. So now you know when your tire was made, but how long should it stay in service? One of the major vehicle tire manufacturers says 6-7 years, assuming safe tread depth remains, which I presume would be a conservative timeframe and also affected by many usage and environmental factors influencing tire integrity and durability.

By the way, once you have located the date code ask yourself if it makes sense given what you know of the tire’s history. My 2721 code corresponded with getting the new trailer in fall of that year. Dave noted a 4423 date code on his new tires, but then found another 4-digit number 1130 on the other sidewall and wondered if that might be a recommended out-of-service date since it would have been about 6½ years after the first code.

Down The Rabbit Hole We Go

Date codes, even if there’s no single steadfast rule for interpreting tire lifespan from them, are probably the most straightforward thing I learned on my trailer tire odyssey. Let me take you down the rabbit hole I followed in the aftermath of the blowout as I explored what to replace it with.

Radial vs Bias Ply Tires

The defining difference between these two lies in the tire’s belt construction. Radial tires are made with steel belts running at a 90 degree angle of the tread center line, while Bias Ply tires have belts (usually nylon) running at a 30-45 degree angle of the tread center line.

Radials have a wider footprint, tend to run cooler and have longer tread life, and are generally tougher overall on account of their steel belts. Bias ply tires may have stronger sidewalls owing to the crosshatch construction and will want to roll straight, which is what a trailer tends to do most of the time. There’s lots of fact and opinion online comparing radial and bias ply tires for trailer use but the bottom line, according to recstuff.com is this: Long Trips, Regular Trailer Use = RADIAL; Short Trips, Tandem axle trailers, Infrequent Use = BIAS PLY

Bias ply are also less expensive than radial, which is perhaps one of the reasons they are the OEM supplied tire for small utility trailers, teardrop campers, boat haulers, and the like. My teardrop came with 5.30×12 bias ply tires (12” being the wheel radius, 5.30” the tire cross section). After the blow-out, I replaced them with ST145-70R12 radials in hopes of having a more robust tire. They had a similar outer tire radius but a broader footprint, which can be clearly seen in the photo of the original tire and its replacement.

Trailer-Specific Tires

Did you notice the letters ST in the tire code of my radials? I was aware of P (passenger car) and LT (light truck) tires but discovered there is also a “Special Trailer” tire type engineered for towed vehicles, which have stiffer sidewalls to resist sway plus higher load ratings.

Tire Load Range

All road-legal tires whether radial or bias ply will have a load range rating, which is essentially a measure of a tire’s strength and tells you how much weight it can carry when inflated to its maximum safe pressure. Load range is indicated by an alphabetic letter (the lowest load weight being B), some of which are subdivided (e.g., C1, C2) to distinguish different maximum load-carrying air pressures.

There is also a measure called a Load Index, which gets more specific than a range, but considering that teardrop trailers are not particularly heavy load shouldn’t be a major factor. My little teardrop, for example, is roughly 800lbs dry weight so around 1000lbs kitted-out and loaded-up. This is similar weight to the Load Range C of the OEM tire which blew BUT remember there are two wheels so that trailer weight is divided in half between them, which means it was far below the max.

I imagine there are performance (or even safety?) trade-offs to trailering with tires having a load range far in excess of actual load but I am guessing there is no down side to having a slightly stronger tire and I feel more confident with the load range E on my new radial teardrop trailer tires.

Treat Your Tires with Care & Concern

Whether or not you upgrade your teardrop camper’s tires from OEM, there are some simple steps which can help maintain tire integrity and durability. Here are some of the maintenance take-aways I brought back up the rabbit hole:

• Whenever possible, locate the trailer with tires out of extended direct sun exposure or cover the entire wheels with a white/light cover.
• For long-term and/or off-season storage, jack up the trailer and lower the axle securely onto blocks or jack stands such that tires are not bearing load.
• With wheels off the ground, reduce air pressure by 10-20 psi. (can’t claim any science to this, but Dave does it with his teardrop and I used to do it when storing my motorcycle off-season).
• Take note of your tire date codes, keep a trip log of distances, perhaps also noting any extended travel on particularly rough roads, so you have some history to refer to.
• Regularly inspect tires for damage and tread wear, and be sure they are accurately inflated before and during road trips.
• Dave had his trailer wheels professionally balanced, which I think is rare but makes a lot of sense when you think about all the vibration if they are out.
• Consider periodically rotating the positions of the three wheels (i.e., 2 active + 1 spare) perhaps at the start of each teardrop camping season.

Speaking of rotation, if you put your teardrop trailer on blocks or jack stands for off-season storage, give the wheels a few turns when you go out every few weeks to say I Love You and thank your trailer for all the good times. The bearings and grease will be happier not sitting in one spot for months on end. (BTW, there’s a whole other “rabbit hole” blog post about bearings coming before winter is out.)

Finally, if you got your teardrop trailer second-hand and do not know its history for a fact, it may be worthwhile to check whether the wheels/tires that are on it match what is on the trailer frame specification plate. If, for example, the plate says inflate to 80psi but the current tires are Load Range C2 (50psi), you may be in for a surprise.

Drawing the Line

A surprising learning outcome of the tire failure was that I hadn’t noticed anything odd in the handling or feel of the trailer until the sight of smoke and then tire rolling off seconds later. I attribute this mainly to driving on bumpy gravel sideroad at the time, and to the teardrop being such a light trailer you often barely feel anything attached to the car (of course, backing up with it is a different story haha).

Hopefully I would have felt something peculiar if the trailer had a flat on a paved road. But frankly I’m not so certain of that, and can’t help but wonder how long I might end up driving before noticing (or someone alerting me to) a tire issue.

A good safety solution would be to install tire pressure sensors, which is high-tech but also high-priced. So, in the spirit of teardrop frugality and simplicity, my answer was to apply a strip of black weatherproof tape horizontally level across the front of the trailer. When I look in my rear view mirror I see the black tape is parallel with defroster lines in the car’s rear window. If the trailer has a flat, the line would be offset and provide another sensory input to warn something is not as it should be.

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Thanks to my teardropping friend Dave (who wrote a guest blog post last year, A Very Flexible Teardrop Power System) for looking over the final draft of this article. I hope there has been something useful to you here, and invite you to share your experiences using the comment form below.