Why the Tyres and Bearings on Your Float Are the Least-Checked Thing You Own
Most trailers get towed and put away. Horse floats and boat trailers do something different: they sit. For weeks at a time, sometimes months, parked beside the shed with the same four (or six, or eight) tyres holding the same air they had the last time anyone looked.
That's the opposite of how a caravan or a daily-driven 4WD behaves, and it's exactly why a tyre pressure monitoring system earns its keep on a float or trailer in a way most owners haven't thought about.
The scale of "sits" is bigger than you'd guess. The Australian Horse Industry Council's 2025 economic and social impact report found that 23% of the nation's horses are transported fewer than ten times a year, and 28% never leave the one location at all. Only around one in ten horses gets floated fifty-plus times annually. Flip that around and most floats in Australia spend the overwhelming majority of their working life parked, not on the road.
Boat trailers follow a similar rhythm, even if nobody's put a precise national figure on it. The Boating Industry Association of Australia's December 2025 report card puts 60% of boating trips at four hours or less, short outings, long storage in between.
None of that is a problem you can see from the driveway. A tyre that looks fine and a bearing that sounds fine can both be quietly heading toward failure, and the two of them fail for reasons that have almost nothing to do with how often you tow.
Compare that with a caravan on a six-month lap, or a 4WD doing the school run. Both get looked at constantly, almost by accident, because they're in daily or weekly use. A horse float gets wheeled out for a competition, a vet trip, or a paddock move, then parked again. A boat trailer gets backed down the ramp on a Saturday and left in the carport until the next long weekend. Neither one gets the casual, repeated attention that catches a slow problem early. That gap is the whole reason this article exists.
The Idle-Time Problem — Why Sitting Still Is Harder on a Trailer Than Towing It
Tyres don't just wear out. They age out, and ageing happens whether the trailer moves or not.
UV light, atmospheric ozone, and daily heat cycling break down the rubber compound and the bond between the rubber and the steel belts underneath it, slowly, from the inside. A tyre can have full tread depth and no visible damage on the outer sidewall and still be structurally compromised, because the cracking tends to start on the inner sidewall, where nobody's looking. Practical Motoring made this point about Australian trailers specifically back in 2017, and the physics hasn't changed since: trailers "do very few kilometres so tyres come up for replacement by age" rather than by wear.
There's no law that catches this. Victoria's VSI 26 roadworthiness standard, which sets the benchmark most states lean on, specifies a minimum tread depth of 1.5mm and says nothing about tyre age at all. As Practical Motoring put it, what's legal and what's safe aren't the same thing. Nobody's required to check the manufacture date stamped into your float's sidewall. Nobody does, until something goes wrong.
Pressure drifts too, quietly, even parked. A trailer that's been sitting for a couple of months is very likely running under its placard pressure before anyone's hitched it up for the trip, not because of a leak, just the ordinary, slow loss every tyre experiences over time.
Wheel bearings have their own version of the same problem, and it's mechanically different from tyre ageing. Grease settles and dries out when a hub sits still for long stretches. SmarterTowing's 2025 breakdown of trailer bearing failure (updated again in February 2026) lists five causes: inadequate or improper lubrication, water contamination, incorrect installation or preload, overloading, and heat transferred from under-inflated tyres. The first of those, drying and settling lubrication, is squarely an idle-time problem: it gets worse the longer a hub sits still, not better.
So you end up with two separate clocks running on a float or boat trailer that never moves much: the tyre clock, ticking down through UV and ozone exposure, and the bearing clock, ticking down through drying grease. Neither one cares whether you're actually using the thing.
There's a third factor that makes both clocks run faster on a float or trailer specifically: they're almost always parked outdoors, on grass, gravel, or a hard stand exposed to full sun, rather than tucked in a garage. A caravan owner who does a big lap every year at least gets the tyres flexed and the bearings turning regularly, rather than sitting static in one position for months on end. A float that goes to three gymkhanas a year, or a boat trailer that only comes out for summer, doesn't get that benefit. It just sits, and sitting is when the damage accumulates.
Horse Floats — Tyre Pressure, Load, and the Welfare Angle Worth Getting Right
A horse float's tyre pressure isn't a single number you can borrow from a mate's rig. It depends on how much the float weighs loaded, and floats carry a genuinely wide range of load.
Get familiar with four terms before you touch the tyre gauge. TARE is the float's empty weight, stamped on the VIN plate near the drawbar. GVM is the maximum weight your tow vehicle itself is rated to carry, fully loaded, before you even hitch the float on. ATM is the Aggregate Trailer Mass: the float plus everything in it, limited by the float's own axles. GCM is everything combined, tow vehicle and float together, the ceiling your tow vehicle's manufacturer sets for the whole rig. A float loaded near its ATM needs more air in the tyres than the same float running empty back from the vet.
Forum consensus among Australian float owners lands in a fairly wide band: light-truck tyres commonly run 40 to 60 psi depending on load and trip length, with one owner on the Stockyard Horse Forums noting 40 psi for regular runs, bumped to 50 psi for a full day's travel. Most LT tyres top out around 65 psi. That's a real spread, not a typo, and it's exactly the kind of range where a set-and-forget system beats a gauge you only remember to check on the morning of a trip.
| Situation | Typical PSI | Notes |
|---|---|---|
| Empty float, short local trip | 40–45 psi | Check tow vehicle's own placard too |
| Loaded float, regular runs | 45–55 psi | Adjust for actual load, not guesswork |
| Fully loaded, long trip | 50–60 psi | Confirm against tyre sidewall max |
| Absolute ceiling (most LT tyres) | ~65 psi | Never exceed sidewall rating |
Always check your float's own compliance plate and the number stamped on the tyre sidewall rather than copying a figure from someone else's rig. Load, tyre brand, and axle configuration all shift the right answer.
Here's where the article needs to be careful, because it's tempting to lean hard on the welfare angle and easy to overstate it. It's a reasonable, common-sense argument that a rough ride from incorrect tyre pressure is unpleasant for a horse standing in a moving float. But we checked, specifically: RSPCA Policy F5 on the transportation of horses covers vehicle type, loading practice, and partitioning to prevent injury. It says nothing about tyre pressure, ride quality, or trailer roadworthiness as a welfare standard. No equestrian or veterinary body currently publishes a formal position linking tyre pressure to horse welfare. So take the welfare point for what it is, a sensible inference, not an official standard, and make the decision on the mechanical merits instead: correct pressure, checked reliably, is safer for the trailer, the tow vehicle, and everyone in it.
The regulatory silence goes further than welfare. South Australia Police's factsheet on towing a horse trailer covers licence class weight limits, mandatory brakes over 750kg GTM, breakaway systems over 2,000kg, and safety chains and couplings in real detail. Tyres, tyre age, and wheel bearings don't get a mention. That's not an oversight specific to one state; it's the pattern everywhere. Nobody is regulating this part of float ownership. It's entirely on you.
A short pre-trip habit covers most of what the regulations don't:
- Check tyre pressure cold, before hitching up, against the float's compliance plate figure.
- Walk the tyre sidewalls for cracking, especially on the inside face where it's easiest to miss.
- Find the tyre's date code and know roughly how old each one is.
- Confirm the float's load is within ATM once the horse, gear, and water are all in.
- Check the display on your TPMS reads all wheels correctly before you pull out of the driveway.
None of that takes more than a few minutes, and all of it is easier with a system that's already told you if something's wrong before you started looking.
Boat Trailers — Salt, Water, and the Bearing Failure Nobody's Warning You About
Boat trailer tyres run higher than most people expect. The typical range is 50 to 65 psi, and the practical target is close to the maximum cold pressure printed on the tyre's sidewall, adjusted for the trailer's actual loaded weight divided by the number of tyres. Australian trailer manufacturer Spitfire Boat Trailers and marine retailer Hunts Marine both land on the same figures, and Hunts Marine goes further, calling under-inflation the leading cause of trailer failure.
| Situation | Typical PSI | Notes |
|---|---|---|
| Light single-axle trailer | 50–55 psi | Match to tyre sidewall rating |
| Heavier dual-axle rig | 55–65 psi | Check per-tyre load, not just total weight |
| Maximum (most trailer tyres) | Sidewall figure | Use as the target, not a ceiling to avoid |
Load distribution matters as much as raw pressure. Hunts Marine's Australian towing guidance recommends roughly 60% of the load sitting forward of the trailer's centre, with tow-ball weight around 10 to 15% of the total loaded weight, to keep the rig stable rather than prone to sway. Get that wrong and no amount of correct tyre pressure fixes the handling problem underneath it.
That's the tyre half of the boat trailer story, and it's the half every competitor covers. The bearing half is where things get more interesting, and where almost nobody in this market is saying anything useful.
Every time you launch or retrieve, you dunk a hot hub straight into cold water. That thermal shock, repeated trip after trip, can compromise the bearing seal and let moisture work its way in, contaminating the grease. SmarterTowing's 2025 analysis of trailer bearing failure names water contamination as a leading cause "particularly for boat trailers," distinct from the ordinary wear-and-tear failure mode that affects any towed axle. Club Marine's Australian boating safety guidance backs this up practically: grease bearings at least once a year, or after particularly sandy trips, and check tyres cold before every haul.
There's a regulatory detail worth knowing too, if you're running electric brakes on anything over 2 tonnes: NSW requires the breakaway system's battery to sustain braking for a full 15 minutes in the event the trailer detaches. It's a narrow rule, but it's the kind of thing that only matters once, on the day you need it.
Here's the gap in the market, stated plainly. Tyredog's own boat-trailer product line markets its sensors as IP67 dust and waterproof, which is a fair selling point for a marine environment. It never once connects that saltwater exposure to the bearing failure risk sitting right next to the tyre it's monitoring. Every boat-trailer TPMS product we looked at talks about tyres. None of them talk about the hub.
Two Ordinary Trips Where the Idle-Time Problem Actually Bites
The gymkhana float, twice a month. The float's been parked beside the shed since the last comp, three weeks ago. Tyres look fine at a glance. You hitch up, load the horse, and head off. If pressure had dropped several psi over those three weeks, unremarkable and unnoticeable just from looking, you'd be towing a loaded float with the tyres flexing more than they should on every corner, generating more heat than the same tyres would at correct pressure, for the entire trip. A dash display that's already flagged the drop means you top up in the driveway instead of finding out on the highway.
The boat trailer, first weekend of the season. It's been under a cover since Easter. You back it down the ramp, launch, spend four hours on the water, then retrieve, and the hot hub goes straight into the water at the ramp, again. If last season ended with the bearings a little dry and this season starts with a fresh dunk in salt water before anyone's checked them, that's the water-contamination mechanism playing out in real time, on a trailer that looks perfectly normal from the outside. A hub temperature reading that's slightly higher than the other side, on the drive home, is the kind of thing you'd never notice by hand on a moving rig, and exactly the kind of thing worth knowing about before it becomes a roadside problem.
Neither scenario needs anything dramatic to go wrong. They just need nobody to have looked closely enough, at the one moment it mattered.
Is TPMS Legally Required for a Horse Float or Boat Trailer in Australia?
No. No Australian Design Rule requires a tyre pressure monitoring system on any trailer type, and that includes horse floats and boat trailers specifically. TPMS is an aftermarket safety choice in this country, full stop, for every vehicle and trailer category.
It's worth repeating the tyre-age point from earlier here, because the two facts sit together: there's also no law setting a maximum tyre age in Australia, just the tread-depth minimum under VSI 26.
Put those two gaps together and you get the actual case for fitting a TPMS to an occasional-use trailer. Nobody is checking this for you. No inspection catches it. No rule forces the issue. The responsibility, and the blind spot, belongs entirely to the owner, and a monitoring system is the difference between finding out about a problem in the driveway or finding out about it at 100 km/h.
How TPMS Actually Works on a Trailer That's Only Sometimes Attached
Strip away the branding and a TPMS is straightforward. Small external sensors screw onto each valve stem, on the tow vehicle and on the float or trailer, and a single display in the cab reads pressure and temperature from all of them at once. No tyre removal, no workshop visit. If you want the full rundown of how the sensors and display talk to each other, and the difference between internal and external sensor designs, our complete guide to how TPMS works covers that from first principles.
The detail that matters specifically for a horse float or boat trailer is how often that data actually updates. Plenty of systems on the market only wake up once you're moving above a set speed, which is a sensible design for a car that's driven daily and a genuinely bad fit for something that sits in a paddock or a driveway for weeks between trips. iCheckTPMS's InstaData™ refreshes every five minutes whether the rig is rolling or parked, which means a slow leak that develops while the float is sitting idle gets caught before the next trip, not discovered on the highway on the way to the gymkhana.
The second piece is IntelliData™, which auto-sets the alarm thresholds when you first screw the sensors onto cold tyres, calibrating a high alarm at roughly 25% above that baseline and a low alarm at around 15% below it. That matters here for a specific reason: owners who tow occasionally are the least likely to go back and manually reprogram thresholds every time load or pressure changes, so a system that sets itself up correctly the first time and stays that way is worth more on a float than on a car you drive every day.
What to Look For in a TPMS for a Horse Float or Boat Trailer (and What Nobody Else Offers)
Four things matter more here than on a standard car TPMS, and it's worth being specific about each one.
External sensors that screw onto the valve stem, not internal ones that need the tyre broken down to fit. Nobody wants to pull a float wheel apart to install a monitoring system, and float and trailer wheels come in enough different sizes and bolt patterns that a system needing custom fitting per wheel is more hassle than it's worth. An external cap-style sensor doesn't care what size the wheel is underneath it; it only cares about the valve stem, which is standard. Our internal vs external TPMS sensors comparison covers the trade-offs in more depth if you're weighing the two up for a mixed fleet.
A genuine IP67 waterproof and dust-tight rating, particularly for anything going near a boat ramp. Sensors that live at the wheel are getting splashed, dunked, and occasionally submerged, and a rating that only covers "light rain" isn't built for that job.
One display that reads both the tow vehicle and the float or trailer together, rather than running two separate systems side by side. Most people towing occasionally don't want to manage two devices for one trip.
And the one nobody else is selling for this application: hub-mounted wheel bearing temperature monitoring, sitting on the hub itself rather than inferred from the tyre's valve-stem reading. This is a physically distinct sensor, not a guess based on tyre temperature. We checked the market carefully before making this claim, because it's an easy one to overstate: neither Tyredog nor Safe-T-Tyre, the two Australian brands with dedicated horse-float and boat-trailer product lines, offer it. TireMinder's US horse-trailer TPMS doesn't offer it either. It's iCheckTPMS's only validated unique differentiator in this market, and given that bearing failure through drying grease and, for boat trailers, saltwater ingress, is a real and separate risk from tyre failure, it's the one feature this category is missing everywhere else.
Here's how a standard TPMS stacks up against what these two trailer types actually need:
| Feature | Standard car/caravan TPMS | What horse floats and boat trailers need |
|---|---|---|
| Sensor type | External or internal | External, no wheel removal for float/trailer axles |
| Waterproof rating | Varies, often light-splash only | Genuine IP67, especially for boat trailers |
| Dual-device pairing | One vehicle only | Tow vehicle + float/trailer on one display |
| Stationary monitoring | Often requires movement to activate | Refreshes while parked (InstaData™) |
| Bearing temperature monitoring | Not offered by any brand reviewed | Hub-mounted sensor, distinct from tyre reading |
Third-party validation is worth mentioning here too. National Cover Insurance's April 2026 roundup of Australia's best TPMS systems places iCheckTPMS third of five brands compared, independent of anything iCheckTPMS says about itself. Neither Tyredog nor Safe-T-Tyre references that ranking in their own marketing, which is a little strange given they're both in the same comparison.
If you want the full mechanics of how bearing failure leads to a caravan fire risk, and why hub temperature is worth watching on any towed axle, our wheel bearing failure and temperature monitoring guide covers that in depth.
Choosing the Right Kit — IC005 vs IC008 for Your Float or Trailer
Two kits cover almost every horse float and boat trailer setup in Australia, and the choice between them comes down to one question: are you monitoring the float or trailer on its own, or the whole rig together? If you're still comparing TPMS brands generally before settling on a kit size, our complete Australian buyer's guide to TPMS is worth reading alongside this section.
The iCheckTPMS IC005 is a 5-sensor kit at $299 AUD, built for monitoring a vehicle or trailer alone: four wheels plus a spare. If your tow vehicle already runs its own TPMS, or you're not worried about monitoring it, the IC005 covers the float or trailer by itself.
The iCheckTPMS IC008 is an 8-sensor kit at $395 AUD, and it's the more common real-world choice for anyone towing occasionally: it covers the tow vehicle and a single-axle float or trailer together, all on one dash display. For someone who hitches up a horse float or boat trailer a handful of times a year, running one system for the whole rig beats juggling two.
Either kit pairs with the optional Wheel Bearing/Hub Temperature Sensor, from $178 AUD for a single-axle (2-sensor) pack, which is the piece that closes the gap described above: hub temperature on the same display as your tyre data, not inferred, measured.
One thing not to overthink: the Signal Booster exists for larger dual-axle rigs or anyone genuinely losing signal at range, but a standard single-axle float or boat trailer sits well within the typical 7-8m transmission range most kits are built for. Don't add it unless you've actually had a dropout.
Worth keeping in mind for anything that sits idle as much as these two trailer types do: the small consumables matter more than they would on a daily-driven vehicle. O-rings on external sensors can perish while a float sits parked through winter, and a sensor left exposed to weather for months benefits from a dust cover between trips. None of this is expensive; replacement O-rings and dust covers both sit around the $5 mark. It's just easy to forget about a part you can't see, on a trailer you don't look at often.
Setting Up and Living With TPMS on an Occasional-Use Trailer
Setup is hand-tight, no tools: screw a sensor onto each valve stem, confirm the display picks up every wheel, and you're done before the first trip.
Because these trailers sit for weeks at a stretch, build in one habit that doesn't depend on the display at all: a quick walk-around before you hitch up, regardless of what the numbers say. A corroded valve stem or a sensor with a flat battery is easier to spot with your eyes than to diagnose from a warning icon.
For boat trailers specifically, hose the sensors and hubs down with fresh water after any saltwater launch. It's a thirty-second habit that directly counters the corrosion mechanism covered earlier: saltwater sitting on a hub or sensor housing between trips is exactly the slow damage that shows up as a bearing problem six months later, not immediately.
For the full mechanical detail on pairing, torque values, and setup steps, our Australian TPMS installation guide covers that ground properly rather than repeating it here. And if you're still deciding whether TPMS is worth it at all for your particular setup, our complete Australian buyer's guide to TPMS is the place to start.
Frequently Asked Questions
Do horse floats need a TPMS in Australia?
Not by law, but they benefit more than most trailers do. Horse floats are towed occasionally and parked for long stretches between trips, which is exactly when tyres age and bearing grease dries out unnoticed. A TPMS catches both before they become a problem on the road, rather than after.
Is TPMS legally required in Australia?
No. No Australian Design Rule mandates TPMS for any vehicle or trailer type, including horse floats, boat trailers, caravans, or 4WDs. It's an aftermarket safety choice, not a legal requirement, and there's also no law setting a maximum tyre age in this country.
What tyre pressure should a horse float run?
Most light-truck tyres on horse floats run 40 to 60 psi depending on load and trip length, with most LT tyres rated to a maximum of around 65 psi. Always check the float's own compliance plate and the tyre's sidewall rating rather than copying a number from another owner's float.
What tyre pressure should a boat trailer run?
Most boat trailer tyres run 50 to 65 psi cold, close to the maximum pressure printed on the tyre's sidewall, adjusted for the trailer's actual loaded weight divided by the number of tyres. Under-inflation is one of the most commonly cited causes of boat trailer tyre failure in Australian retailer guidance.
Can one TPMS monitor both my tow vehicle and my float or boat trailer?
Yes. An 8-sensor kit like the iCheckTPMS IC008 covers a tow vehicle, four wheels plus a spare, and a single-axle float or trailer, on the same dash display. You're reading the whole rig as one system rather than managing two.
Why do boat trailer wheel bearings fail even on a well-maintained trailer?
Launching and retrieving repeatedly dunks a hot hub into cold water, and that thermal shock can compromise the bearing seal and let moisture into the hub, contaminating the grease. It's a distinct failure path from ordinary wear, and SmarterTowing's analysis of trailer bearing failure names water contamination as a leading cause "particularly for boat trailers."
How often should I check tyres and bearings on a float or trailer I don't use often?
Check tyre pressure cold before every trip, no matter how long it's been sitting, because pressure drops slowly even while parked. Grease wheel bearings at least once a year, or straight after any trip through sand or saltwater, per Australian boating safety guidance.
Which iCheckTPMS kit suits a horse float or boat trailer?
The IC005 suits monitoring the float or trailer on its own. The IC008 covers the tow vehicle and a single-axle float or trailer together on one display, which suits most owners towing occasionally. Either kit pairs with the optional Wheel Bearing/Hub Temperature Sensor for hub monitoring alongside the tyre data.
Do horse floats and boat trailers need special TPMS sensors?
No. External cap-style sensors screw onto any standard valve stem regardless of the wheel size or bolt pattern underneath, so the same sensor works on a car, a horse float, or a boat trailer. What matters more is the waterproof rating, since these sensors sit exposed at the wheel through wet launches and long stretches of outdoor storage.
What's the biggest difference between monitoring a caravan and monitoring a horse float or boat trailer?
Usage pattern. A caravan doing a big lap gets checked constantly just by being in near-daily use. A horse float or boat trailer sits idle for weeks between short trips, so the monitoring system needs to keep working while parked, not just while towing, which is why stationary refresh matters more here than on a rig that's rarely still.
