tyre wear

[pablo0874]

i was wondering if anyone knows how long usually front tyres last on the terrrano ?
its just ive a new set put on about a yr ago at tyres ,no brand name just cheapest from my local good tread on em an that , but noticed today they seem very worn on both sides mostly on inner ,down to the marker ,is that normal i had two get two drop links renewed last yr on mot , but had tracking checked and didnt need it , it never pulls to any side whilst driving or braking etc and if i leave go of the wheel while driving it runs straight ,is this normal or would it be a case of cheap tyres you get what you pay for ,£69 each?
ps. i dont use it off road neither or drive crazy .