I have noticed i have a screw in the drivers side front tyre, and looking where it is i don't think a repair is an option.
So looks like i might need a new tyre, how many tyres ahould i be changing and WHY if more than one?
how worn is the other front tyre?
I'd just replace the one with the screw (with the same make/model as the other front)...unless the other front is nearly on it's way out and then I'd replace both front.
there is plenty of life left in the other, just i have heard some people saying you should replace in pairs just wondering what the reason is, and for a car that gets driven sensbly, ie i don't ramp the crap out of it on country roads, whether there is any reason.
no reason. you'll get more grip if the tyres are paired front and back than having 4 different tyres on each corner but if you've got one tyre with 5mm on the front passenger and a new tyre with 8mm on the front drivers side (of the same make/model) you'll be just fine.
As I said, just get the same make/model as the other front tyre.
Or, if the spare [if you have a proper one] is new
swap it for the old, good front and get another to match