It is possible that the tyres/metallic/non-metallic parts of the aircraft come in contact with some particles in air, while traveling at high speeds in air. They may get static charges. In order to remove the static charge from the body of the plane, the tyres may be made slightly conducting. So as soon as the tyres land on the ground, the static charges from the plane go into the Earth.
It is also possible that when the air plane takes off and lands, there is a lot of friction between the tyres and the ground. This could generate static charges. That would damage the craft and also give shocks. So tyres are made of slightly conducting special rubber.
ordinary rubber is an insulator.