$\ce{C6H5C(CH3)3}$ is attacked faster than $\ce{C6H5CH3}$ in nitration, presumably because of the greater +I effect. However, for chlorination $\ce{C6H5CH3}$ is attacked faster i.e hyperconjugation takes over. Why?
One explanation given in my textbook is that chlorination is a less polar reaction. But I don't understand how that affects the relative importance of hyperconjuative/inductive effect.
