I started preparing this answer hours ago before I saw Jane's reference but didn't have time to finish it. The fact that we both came to the same conclusion reinforces my suggestion.

Here's an explanation in Spanish:

3 - Proceso de extrusión
"El rodamiento y la goma de los costados (dos compuestos de goma distintos) se moldean en sus formas específicas mediante tubadoras. Las tubadoras producen una banda continua de goma que después se enfría y corta a las longitudes especificadas."
http://html.rincondelvago.com/neumaticos_2.html

It says here "tubadora o extrusor":

"1.3.5 Extrusión
El siguiente proceso que tiene lugar es el de extrusión, que consiste en
el paso de los productos a través de la tubadora o extrusor. "
https://www.iit.comillas.edu/pfc/resumenes/4a431da9c09e7.pdf

So I think "extrusion" is probably what it means.

"The softened rubber from the feed mill or homogenizing mill goes into the
extruder. The two major tire parts that are formed by extrusion are the sidewall and the tread. These parts are constructed by forming two specific compounds into tread profiles by feeding the rubber through an extruder. Other parts include the apex. Extruders produce continuous lengths of treads, which are cooled and cut into specific lengths."
https://tirenews4u.wordpress.com/2010/08/16/extrusion/

rubber Extrusion Operator Jobs | Glassdoor
https://www.glassdoor.com › Extrusion Operator
Perform other duties as directed by the Extrusion Department Manager… .... and/or assist in the operation of calendars, extrusion lines, and other… subsidiary of ...