Ground in electrical is anywhere you define as 0V, which in a car is the chassis. On the grid it is called “earth ground” or bonding.
Any voltage rise or noise from current drawn must be considered on grounds with appropriate connection for minimum R and L of the cable to stay as close to 0V as necessary to function.
The tires are good insulators and ESD from triboelectric friction cause charge the vehicle , like walking on nylon carpet with neoprene shoes, but contaminants and humidity discharge this for the most part.
I once asked my nephew , who is an exec. at Michelin if they added carbon to improve static dissipation. His research indicate there was none. I know that all tires are ionized with UHV GV radiation to crosslink the polymer for durability. This is also the same method to zap impurities in plastic to make them better insulators. So it seems to be a conflict between durability and electrical conductivity.
But for all onboard electronics, you just need a local ground to work like everything is floating at some point, even the earth! The grid is a much greater risk without earth bonding.