A wheel is made of:

• a rim, which supports the tyre,
• a disc allowing all to be attached to the hub.

The “rim” word stands in reality for the wheel. The steel wheels are made of a disc and a rim that are assembled and welded.

The wheel is attached to the hub thanks to the flat face of the disc.

The rim directly receives the tyre. The rim designation indicates the rim system, its dimensions and its profile. There are 2 types of rim: drop centre 1 piece or multi-parts that enable changing the tyres without strength instruments. They are however heavier, out-of-round and out-of-true.

The disc is developed in order to get the best possible match between the load capacity and the weight of the wheel, by respecting the following constraints: attachment to the hub, bulk and brake ventilation.

The classic wheels used to be mounted on axles which were equipped with drum brakes. The valve and the drum turn together around the axle.

When a classic wheel is mounted on an axle equipped with drum brakes, the wheel and the valve turn around the calliper.

If an object enters into the wheel, it is stuck between the valve and the calliper. Then the valve gets twisted or cut, according to the size of the object. This type of incident can result in a violent blowout. To protect the valve, an efficient solution consists in putting it on the other side of the disc.

Equipped with a double drain valve, the reversible wheel for semitrailers and trailers allows, if needed, to turn the wheel/tyre set.

This specificity allows avoiding the tyre disassembly recommended in order to even the wear of tyre tread profile.

It also allows preparing wheels without thinking about the mounting-on-vehicle side.

Positive
IS = INSET for single wheel
Negative
NIS = Negative Inset
Double wheel
OS = OFFSET

A wheel’s load capacity is the potential load for a defined speed. It must be identical to the load approved by the vehicle manufacturer.
The load capacity codes for the wheel use the codes defined by the ETRTO for the tyre.
According to the standards, the load capacity for double mounting is smaller than for single mounting.

The wheel is a safety device. It is recommended to check it frequently to be sure there is no distortion, major wear, corrosion, break or crack. The paint and bearing surface condition on double wheels must be frequently checked, particularly during operations on the tyres.

To retain the warranty of an efficient clamp, the reversible steel wheels must not be repainted if they are turned. For other wheels, it is imperative to avoid any risk of paint excess thickness on the bearing surfaces and on nut seats.

The anti-rust paint on the rim and on detachable flanges in permanent contact with the tyre beads must always be in good condition. They must be refurbished if needed.

The EUWA ES 3.06 (Association of European Wheel Manufacturers) recommends to replace wheels with 10% wear in the area of the rim flange pour some use conditions of heavy use: seashores, winter (salt), mud and sand. This wear, caused by the friction between the rim flange and the tyre is emphasized when underinflating or in case of vehicle overload.

Before being mounted, the assembly elements (hub attachment face or brake drum and wheel) must be cleaned from any impurity (mud, rust, grease, tarmac, etc.)

Concerning the mounting, here are the safety recommendations:

• Use the fixing elements recommended by the manufacturer (flat, spherical, conical, thread)
• Replace faulty nuts and screws
• Slightly oil (don’t grease!) stud and axle threads and flat or needle-nose nut bearing surfaces (don’t oil the spherical or conical nut seats).
• Tighten the nuts with a torque wrench with respect to the torque.
• Use the impact wrench only to untighten, never to tighten.
• Check the nut torque about 50km after the mounting, then at regular intervals.

Nut screwing order