Transportation of a boat is not just a movement from point A to point B, but a process that requires a reliable technical base. Wheels on the boat trailer These are one of the most critical safety features, as they take on the main dynamic load during the driving on the track and in the manoeuvres on the descent to the water. Many owners underestimate the importance of choosing the right tires, relying on "what was included", but this often leads to unpleasant surprises right at the start of the season.
A mismatched or worn out ramp can cause an accident, damage to an expensive boat or motor. trailer-rubber It has its own unique design and labeling specifications that you need to consider when buying, and in this article we will discuss in detail how not to get confused in size, what is the load index and why you can not put tires on a trailer.
Key differences between trailer rubber and automotive
At first glance, the wheel is the wheel, but the devil is in the details of the cord. Car tires They are designed to withstand side loads when cornering, so their sidewall is often softer and more flexible. Trailer rubber (marked with the letters ST - Special Trailer) has a stiffer sidewall and a reinforced frame, since the trailers do not turn the wheels, but go along the arc, creating huge friction and heating.
The use of rubber on a boat trailer is a risk that can result in the tire exploding at high speed due to overheating. ST-tyre It's specially reinforced for vertical loads and minimizing trailer swelling, and in addition, the tread on specialized models often has a directional pattern for better water drainage, which is critical when launching a boat into a reservoir.
⚠️ Warning: Never use a tire marked "P" (Passenger) or "LT" (Light Truck) instead of "ST", unless the trailer manufacturer allows such a change explicitly.
It is also important to pay attention to the age of the rubber, because even if the tread looks new, but the tire is 5-6 years old, it is prohibited to use it under full load, and the rubber tans over time and loses its elasticity, which leads to microcracks.
Always check the production date on the sidewall of the tire. The four digits in the oval (e.g. 3523) mean the 35th week of 2023. Do not buy tires older than 3 years from the date of release.
Decoding of marking and size selection
Choosing the right size isn't just a matter of whether the wheel fits into the arch, but the main marking is applied to the sidewall and looks like a set of numbers and letters, for example. 175/80 R13 or 205/75 R14CThe first digit (175 or 205) indicates profile-width The second digit (80 or 75) is series, that is, the ratio of profile height to width, expressed as a percentage.
The letter "R" stands for radial cord design, which is the standard for modern trailers. The last number (13, 14, 15) is the radial cord design. landing-diameter A mistake in choosing a diameter even per inch will make it impossible to install, because the tire will simply not wear on the disk or will hang around.
For boat trailers, models with the C-sized index are often used, indicating a reinforced design for commercial vehicles. This is a good sign for increased wear resistance. Below is a table of correspondence of popular sizes for different classes of trailers.
| Tyre size | Disk diameter | Max. load (per axle) | Typical application |
|---|---|---|---|
| 155/80 R13 | 13 inches | 1,000 kg | Small PVC boats, catamarans |
| 175/80 R13 | 13 inches | 1200 kg | Boats 3.5-4.5 m, light aluminum |
| 185/60 R14 | 14 inches | 1400 kg | Medium-sized boats, motorboats |
| 205/75 R14C | 14 inches | 1,600 kg | Heavy boats, cabin options |
| 215/60 R15 | 15 inches | 1800 kg | Large boats, yachts on the trailer |
When replacing tires, always focus on the trailer manufacturer's sign, which indicates the total weight. The total load capacity of all wheels should exceed the weight of the trailer with boat and equipment by at least 10-15%.
Load capacity calculation and load indices
One of the most important parameters is load-pointThis is a numerical code that tells you how much weight a wheel can handle at top speed, and for boat trailers, this is critical because water adds weight, and braking dynamics creates inertia.
For example, if the load index is 90, this means that the wheel can withstand 600 kg. Since there are two axles, the total load will be 1200 kg. However, you should never load the trailer "to the tie". Safety margin You need to compensate for blows from pits and irregularities of the road.
Also consider speed. The load index is valid at a certain speed (usually up to 100-110 km/h for trailers). If you plan long runs along the highway, it is better to take wheels with a margin on the index to reduce heat.
⚠️ Note: When calculating weight, be sure to add the weight of the full fuel tank, anchor, gear and trailer itself. Often owners only count the weight of the boat hull, which is a gross mistake.
Tire pressure: myths and reality
The issue of pressure in trailer-tyre The rule is that you need to pump to the pressure specified by the tire manufacturer for maximum load, not the sensation of "eye". Usually for trailer tires, this value is from 3.0 to 4.5 atmospheres (bar).
Under-performing tires are the main enemy of trailer rubber, and at low pressure, the sidewall begins to deform actively (walk) at each wheel turn, causing instant and intense heating of the inner layer, which leads to the stratification of the frame and explosion. Pumping is also dangerous, but for a trailer it is less critical than under-pumping, although the comfort of traction decreases.
You only need to check the pressure on the cold tires before you start driving, and after 10-15 kilometers, the pressure inside will increase due to the heating of the air, and the pressure gauge will be incorrect. Use a quality gauge, because the readings at gas stations are often false.
☑️ Checking the wheels before the season
Discs: steel or light alloy?
Choosing the wheels for the boat trailer is an eternal battle between budget and aesthetics. Steel discs. (Pressed) is a classic of the genre. They're cheap, they're durable, they're easy to repair. But they have one big drawback: they rust. Saltwater contact, washing and storage in a wet garage quickly turns steel into iron oxide.
Alloy wheels They look much more presentable, and more importantly, they don't corrosion to the same degree. Aluminum oxidizes to form a protective film, but it doesn't rust through. It's also lighter, which reduces unsprung mass a little bit. But here's a caveat: cast discs are afraid of hitting curbs or rocks on the descent -- they can crack, not bend, like steel.
The most important parameter of the disk is squabble For trailers, the most common 4x100, 4x112, 5x112 or 5x130 circuits. A choice error will result in the wheel simply not standing on the hub. Also pay attention to the disk departure (ET) so that the wheel does not rub against the elements of the frame or the side of the boat.
Secrets of care for steel discs
If you use stamped discs, be sure to treat the inside with a corrosion-resistant compound immediately after purchase, they are coated with paint on the outside, and often left unprotected inside, starting to rot from the inside, regular washing with fresh water after going to sea is mandatory.
Replacement and balancing of wheels
Replacement of rubber on the discs requires special tools, and it is extremely difficult and dangerous to "re-wheel" a high profile rigid trailer tire at home, and it is better to contact a tire that specializes in freight or trailer wheels.
Balancing for boat trailers is often ignored, and this is only true for very low speeds (up to 60 km/h). imbalance This will cause a beat that will be transmitted to the trailer frame and eventually to the boat's transom, and the constant vibration can shake the fasteners.
When installing new wheels, be sure to use a dynamometer key. The nut tightening moment for standard M12 bolts is usually about 90-110 Nm. A drag can lead to stud deformation, and a tightening can lead to spontaneous unwinding of the wheel in transit.
After the first 50 km of running on new wheels, be sure to repeat the bolts. The metal has the property of seating, and the initial moment of tightening may weaken.
Remember the spare wheel. It has to be exactly the same as the main wheel, and most importantly, pumped, and it often happens that at the time of puncture, the spare tire is empty or with dried rubber.
Frequently Asked Questions (FAQ)
Can I put on the boat trailer wheels from a passenger car?
Technically, you can, if the slatting and the diameter match, but this is not recommended. Passenger tires (marked P) have a softer sidewall and are not designed to work for long periods without side-screwing, which is typical for trailers, this increases the risk of explosion on the track.
How often should the wheels on the trailer be changed?
The resource depends on the mileage, but the main factor is time. Even if the tread is whole, the rubber mixture should be changed every 5-6 years due to the aging of the material. Visually, the aging is referred to as small cracks ("web") throughout the profile.
Which is better: chamber or tubeless tires?
For boat trailers, tubeless tires are standard; they are lighter, less warm and safer (lower when punctured), and chamber models should only be installed on older discs that do not hold air without a camera.
Should I release the pressure before launching the boat into the water?
No, modern tires don't require a reduction in pressure to get into the water, but instead, it can damage the tyre side to the disc, and keep the pressure normal, according to the manufacturer's specification.
Why is the inside of the tire washed off?
This is often a sign that the axle of the trailer has a deflection or a broken wheel angle (convergence).