Method for determining a tread depth (td) of a tread of a tyre during operation of a vehicle having the tyre , wherein the method comprises the following steps: - determining an instantaneous rotational speed (ω) of a wheel (W), having the tyre , of the vehicle based on data (D) determined by at least one first sensor , - determining an instantaneous speed (v) of the vehicle based on data determined by at least one second sensor which is different from the at least one first sensor , - determining an instantaneous dynamic wheel radius (r1 dyn ) of the wheel (W) having the tyre based on the determined instantaneous rotational speed (ω) and the determined instantaneous speed (v) of the vehicle , - determining at least one first operating parameter of the tyre , selected from the group consisting of an instantaneous tyre temperature (T), an instantaneous tyre pressure (p) and an instantaneous tyre load (RL), - determining an instantaneous dynamic inside radius (r2 dyn ) of the wheel (W) based on the at least one determined first operating parameter, wherein the inside radius of the wheel (W) is the distance between a wheel centre and a tyre-side start of the tread , - determining a tread depth (td) of the tread of the tyre based on the determined instantaneous dynamic wheel radius (r1 dyn ) and the determined instantaneous dynamic inside radius (r2 dyn ), characterized in that the method further comprises: - determining at least one further first operating parameter (SL, DT, BE) of the tyre , selected from the group consisting of an instantaneous roadway gradient (SL), an instantaneous vehicle drive mode (DT) and an instantaneous tyre material expansion (BE), and in that the instantaneous dynamic inside radius (r2 dyn ) is further determined based on the at least one determined further first operating parameter (SL, DT, BE) . - determining an instantaneous rotational speed (ω) of a wheel (W), having the tyre , of the vehicle based on data (D) determined by at least one first sensor , - determining an instantaneous speed (v) of the vehicle based on data determined by at least one second sensor which is different from the at least one first sensor , - determining an instantaneous dynamic wheel radius (r1 dyn ) of the wheel (W) having the tyre based on the determined instantaneous rotational speed (ω) and the determined instantaneous speed (v) of the vehicle , - determining at least one first operating parameter of the tyre , selected from the group consisting of an instantaneous tyre temperature (T), an instantaneous tyre pressure (p) and an instantaneous tyre load (RL), - determining an instantaneous dynamic inside radius (r2 dyn ) of the wheel (W) based on the at least one determined first operating parameter, wherein the inside radius of the wheel (W) is the distance between a wheel centre and a tyre-side start of the tread , - determining a tread depth (td) of the tread of the tyre based on the determined instantaneous dynamic wheel radius (r1 dyn ) and the determined instantaneous dynamic inside radius (r2 dyn ), characterized in that the method further comprises: - determining at least one further first operating parameter (SL, DT, BE) of the tyre , selected from the group consisting of an instantaneous roadway gradient (SL), an instantaneous vehicle drive mode (DT) and an instantaneous tyre material expansion (BE), <EOS>