The maximum acceleration a tyre can take is μg, a constant, independent of the mass of the car! While
the maximum force a tyre can take depends very much on the current vertical load or weight on the
tyre, the acceleration of that tyre does not depend on the current weight. If a tyre can take one g before
sliding, it can take it on a lightweight car as well as on a heavy car, and it can take it under load as well
as when lightly loaded.