From the construction of their sidewalls and tread to the ply and structure - vehicle and trailer tyres are built differently. It’s one of those things that perhaps you’ve never stopped to consider, but if you own a trailer, are looking to replace your trailers’ tyres or are in the market for a trailer, then it’s important for you to know and understand these differences.
The functions and duties that your vehicle performs - from steering, transmitting power from the engine to the road and the ability to swerve and avoid obstacles, vary greatly to those required of a trailer. In other words, a trailer’s tyres don’t need to perform all these functions. Truck or car tyres are designed to be on a lead vehicle - their tread is thick to maintain traction on slippery roads and sharp turns. Trailer tyres however, are designed for, yep, you guessed it - a following vehicle. Trailer tyres have thicker sidewalls to handle debris and other objects that may come their way. The tread on a trailer tyre doesn’t tend to be as thick either - this means that they aren’t as capable at maintaining traction.
So what are trailer tyres ‘good’ at? One of the most common problems associated with towing a trailer is ‘trailer sway’. This occurs when your trailer sways from side to side while the tow vehicle is driving straight. This can be very dangerous and in the extreme, the swaying can get so bad that the trailer loses traction and slides sideways - taking your tow vehicle with it. Thankfully, trailer tyres are designed to accommodate the sway that trailers typically experience - that’s what they’re good at, and that’s why you need to ensure that you have the correct tyres fitted to your trailer.
‘ST’ tyres, which stands for ‘Special Trailer’ tyres, are designed for your trailer’s specific needs. Their stiff sidewalls, as mentioned, help prevent your tow vehicle from swaying. They have a heavy-duty load capacity, which can accommodate 40% more weight than passenger (P) tyres. ST tyres are typically narrower than those on a car and are designed to specifically fit your trailer wheels. Their shallower tread means that they wiggle less and work to improve your tow vehicle’s fuel efficiency and run cooler.
Compared to how often you use your vehicle, a trailer’s tyres typically tend to do far fewer kilometers before they will need to be replaced. A vehicle’s tyres will usually need replacing due to wear, whereas a trailer’s tyres usually need replacing because of their age, even though they may have plenty of tread left. Trailers can often sit around in the one spot for days or weeks at a time, exposed to the elements, including sunlight, which can cause damage to the tyres.
When it comes to selecting tyres for your trailer, you should always buy tyres that are the correct size, type and load range, as recommended by the manufacturer. This information can be found in the owner’s manual or on the trailer’s certification label. Just like a vehicle’s tyres, trailer tyres have a load rating, located on the sidewall of the tyre, which indicates the amount of weight that they can safely carry. It’s super important to adhere to this indicator as overloading your trailer can lead to a large heat build up, causing accelerated wear or a dreaded blowout.
To get the most out of your trailer tyres, show them some love. Due to the hard sidewall construction on trailer tyres, they won’t show signs of sagging when in need of inflation. You need to check your tyre pressure with a quality gauge and should do this regularly (and don’t forget to check the spare while you’re at it!). If your trailer has been sitting idle for awhile, you should definitely check the tyre pressure before loading your trailer up and heading off. If your trailer is likely to be sitting unused for periods of time, store it in a cool, dry place where possible, or cover your tyres for UV protection. Afterall, a trailer is a super handy piece of equipment to own and often the envy of your mates. You want to keep that thing in perfect running order, as no one is going to give you that six pack of cold ones they promised you if they could borrow your trailer when they wind up on the side of the highway with a trailer tyre blowout.