A very robust strength of tires have now been introduced in karachi named as Tri-ace .Its a Usa enginered brand and is manufactured in almost all the sizes of passenger car . Its a little expensive tire but its quality justifies it . I think the new brand will compete with the Japani Yokohama . It is available in only few shops in Karachi . I know two of them which is Mohsin Tire Corp in Bahadurshah Market and Masterwheel Alignment in Shadman Town phase 1 karachi.