Have a look at some of the strings both in the bar and the Discovery forum, ask a question like this and everybody has a different opinion (I hope mine havn't upset anybody) and I personally believe that price should not be the factor which make you decide which tyres to buy. That said I have found brands like Khumo and General very reasonable, also Marshal are worth a look but if your not planning to trash the tyres on your first green lane then remember you get what you pay for, I would spend the time shopping around for the best price on a brand you recognise and keep remoulds where they should be, off the road (in the mud I mean).
