Manufacturing

Have you ever wondered how Geestone tyres are made? Each tyre undergoes an extensive process beginning with raw materials and ending with a final inspection. This ensures that each tyre is made with the same attention to quality that our company is reputed for.

Mixing the materials

Various grades of natural and synthetic rubber are combined with carbon black, sulphur and chemical products in an internal mixer to meet specific compound requirements. The resulting blend is called the "master batch", which is formed into rubber sheets, and cooled. Some rubber is used for additional processing while the majority is prepared for the extruding stage

Extruding the tread

Heat is applied to the rubber to make it more elastic and then it is put through extruders machines where the tread and sidewalls, which require two different rubber compounds, are formed into the required shapes. The extruders produce a continuous sheet of tread rubber, which is then cooled and cut to specific tyre lengths.

Weaving the plies

Spinning cords such as rayon, nylon, steel and polyester undergo a process called “calendering”, where they are woven into sheets and coated with rubber on both sides. Once this is finished, the sheets are then cut at the proper angle into specific widths and lengths and eventually used for casing and cap plies, while steel cords are used for the belts.

Preparing the bead core

The bead core is formed by aligning, and then coating plated steel wires with rubber. After, it is wound on a coil a certain number of times to form bead rings, which provide a specific diameter and strength for a particular tyre.

Building process

The building process involves two stages. Stage 1: Beginning with the woven sheets, the inner liner, body plies and sidewalls are placed on the building drum. The correctly-positioned beads rings are then attached, which results in the automatic wrapping of the ply edges around the bead core, and the simultaneously movement of the sidewalls into position. Stage 2: The tyre is shaped by inflating the rubber and applying sidetread rubber, two steel belts and a cap ply to achieve a "green" tyre.

Vulcanisation

The “green” tyre is placed in a curing press for a certain period of time (10-15 minutes) at a specific pressure and temperature. Once heat and pressure has been applied to the tyre, it is then removed from the mould having achieved its final size, shape and tread pattern.

Trimming

Excess rubber from the curing process is removed, and the tyre is trimmed to order.

Final inspection

Each tyre is visually and electronically inspected for balance, quality and uniformity. This final check ensures consistent and reliable performance.