Loss of tyre pressure

[redfox1]

Hi everyone,Just a quick question-how common is it for the wheels to  become corroded ?.I'm asking as both my front and rear tyres are losing roughly about 1psi a day.I have had them refitted by a tyre tech,but they still leak about the same amount,and he did mention possible corrosion-has anybody else had this problem,and short of new wheels,is there anything else I can do?