Tyres quality concern

Fellow south African, I am raising a concern about the quality of tyres Malas sells. I always go there because it is relatively cheap, and they have some special for government employees but all the tyres I buy there don't last as long as the tyres which came with the car. I noticed that the tyres normally start cracking way before the tyre thread are finished, I don't think that is normally for a car that driven almost daily.