What's causing my 2001 Toyota Yaris to lose tyre pressure?

My 2001 Toyota Yaris is loosing tyre pressure on all four wheels even after treatment by Inchcape for corrosion. I have to top up every few days.

Asked on 13 July 2013 by ER, via email

Answered by Honest John
If it's on alloy wheels then your best bet is to swap to a set of steels wheels for a 51 Yaris from a scrapper or breaker. The alloy wheels will have become porous and there is nothing effective that can be done.
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