  We estimate the Hoelder exponent $\alpha$ of solutions to the Beltrami
equation $\dbar f=\mu\de f$, where the Beltrami coefficient satisfies
$\|\mu\|_\infty<1$. Our estimate improves the classical estimate
$\alpha\ge\|K_\mu\|^{-1}$, where $K_\mu=(1+|\mu|)/(1-|\mu|)$, and it is sharp,
in the sense that it is actually attained in a class of mappings which
generalize the radial stretchings. Some other properties of such mappings are
also provided.
