How tight should I tighten flange nuts?

Always use a torque wrench when tightening the flange nut. All flange nuts must be tightened with 280-300 Nm.

What is the difference between a flange nut, a hub nut and a castle nut?

Flange nut, hub nut and castle nut are all names for nuts used to secure wheel bearings on trailers. The flange nut has an integrated flange that spreads the load evenly over a larger area. The hub nut sits directly on the wheel hub and secures the bearing. The castle nut has slots in the top through which a split pin can be fitted for extra security. On modern trailers, flange nuts tightened to a set torque are usually used instead of castle nuts with a split pin.

What torque should be used for wheel bearings on a trailer?

For wheel bearings on a trailer the flange nut should always be tightened to 280–300 Nm, whether it is an AL-KO bearing or another make. This applies to most standard trailers with compact bearings. Always use a torque wrench to be sure of the setting. A wheel bearing that is too loose will wear unnecessarily, while one that is too tight can be damaged.

How do I tighten a trailer wheel bearing correctly?

First clean the threads and check that the nut turns easily by hand. Then use a torque wrench set to 280–300 Nm and tighten the nut in one smooth movement. After tightening, the wheel should turn freely without resistance or play. We recommend checking the torque again after the first 500 km.

What tightening torque applies to trailer wheel bolts?

The tightening torque for trailer wheel bolts varies with the bolt size and the type of rim. For M12 bolts the normal torque is 90–110 Nm, for M14 bolts 120–140 Nm and for M16 bolts 160–180 Nm. Always check the manufacturer's specification for your particular trailer. Tighten the bolts crosswise in several passes for even loading.

Can I use the same torque for every nut on the trailer?

No. Different nuts on a trailer need different torques. Flange nuts for wheel bearings are tightened to 280–300 Nm, while wheel bolts take considerably less depending on their size. Jockey wheel nuts and coupling bolts have their own figures too. Always use the right torque wrench and follow the manufacturer's instructions for each component.

Do I need special tools to change a trailer wheel bearing?

You need a torque wrench that reaches 280–300 Nm, which is more than most standard wrenches manage. You also need a socket to fit the flange nut, usually 52–55 mm. A bearing puller makes pressing out the old bearing considerably easier. We carry special tools for the most common trailer makes.

What happens if the flange nut is overtightened?

Overtightening can cause several problems. The internal components of the wheel bearing can be damaged, which leads to increased wear and a shorter life. In the worst case the bearing can seize completely, so the wheel no longer turns freely. That is why it is important always to use a torque wrench and stay within the recommended range of 280–300 Nm.

Is the torque different for compact bearings and taper roller bearings?

Yes, the two bearing types are tightened differently. Compact bearings, which are the most common on modern trailers, are tightened to a fixed torque of 280–300 Nm. Taper roller bearings need a different technique: you tighten first to seat the bearing, then slacken slightly and tighten again to a lower torque. Follow the manufacturer's specific instructions for your bearing type.

Can flange nuts be reused when changing a bearing?

Often not — and on AL-KO compact bearings, never. The AL-KO hub nut is a one-shot nut: the thread locks as it is torqued up and is damaged when the nut is removed, so a new nut must be fitted every time the hub is disturbed. Always check the specification for your own axle before reusing a nut, and replace any nut that shows wear, corrosion or damaged threads. We stock replacement nuts for all the common trailer makes, including AL-KO, BPW and Knott.

How often should the wheel bearing torque be checked?

The torque should be checked after the first 500 km with a new trailer, or after a bearing change. After that we recommend checking it at every service, or at least once a year. If the trailer is used frequently or in demanding conditions, more frequent checks are worthwhile. A correctly tightened wheel bearing extends the life of both the bearing and the tyres.