Cast magnesium builds up stresses while driving, and those stresses do not entirely come back out by themselves. They may also age-harden and harder usually means more brittle. Stories abound of magnesium wheels without tires cracking during rack storage! The U.S Military developed an annealing process to stress-relieve such wheels on high performance fighter planes. Powder-coating if done properly will also stress-relieve magnesium wheels. The keys are to get the entire wheel up to 275F and keep it there for a while, followed by extremely slow cooling- overnight is best. This temp will cause the Argent Silver paint to turn tan, requiring repainting. And because zinc chromate primers are difficult to find today, aggressive blasting is not needed nor recommended. The silver paint is decorative; the chromate primer is vital!