It's been my opinion, that new Lexus automobiles are coming with Nitrogen, and the dealers are refilling them with nitrogen at no cost. Look at your valve caps, if they have green end caps, the tires came with nitrogen. Both my wife's ES and my F came with nitrogen. Her caps are marked N2, and mine are marked nitrogen in little tiny letters with a larger 2. IMO, your dealer owes you $50.
Lou
Lou