Which aluminum alloy grade is suitable for automobile wheels?

Automobile wheels require a strong and lightweight material that can withstand the weight of the vehicle and the stresses of driving. Aluminum alloys are commonly used in automobile wheels due to their desirable properties. The most suitable aluminum alloy grades for automobile wheels are those that fall under the 6000 series. These alloys have good strength and are easily weldable. Specifically, 6061 and 6063 alloys are commonly used in automobile wheels due to their excellent machinability, corrosion resistance, and strength.

For good strength, easy machineability, low cost, and the ability to take an excellent polish, you'd use 6061. 6063 is not a smart choice.

The only advantage 6063 would have over it is a slight increase in corrosion resistance - but it's not an issue because wheels are coated. 6063 aluminum has higher thermal conductivity (not ideal for car wheels), lower yield strength, and lower fatigue strength. It's also more expensive.