Let d≥2 and D≥1. For p∈{4,∞}, let Cp(d,D) be the maximum of the ratio
∥u∥L2(Sd)∥u∥Lp(Sd)
where u ranges over (real) spherical harmonics of degree D on the d-dimensional sphere Sd, which we normalize to have unit measure. Establish upper and lower bounds on Cp(d,D) that are as strong as possible.