Christian Horner aims 'Red Bull' joke at Zak Brown after 'tire water' taunt

Christian Horner has responded to Zak Brown's playful mocking at the Miami Grand Prix, after the American was seen drinking from a bottle labelled "tire water" during practice. Red Bull's lingering suspicion of McLaren using illegal practices to regulate the temperature of its tyres has come back into sharp focus at the Miami International Autodrome this weekend. Towards the end of last season, Auto Motor und Sport (AMuS) reported the Milton Keynes team had accused the papaya squad of using water to cool its tyres, a move that would allow the now-reigning constructors' champions to better prevent degradation and keep its Pirellis in the optimal operating window for longer. Although the FIA found no evidence to support those claims, according to Motorsport.com , Horner and co. were evidently unconvinced as AMuS is now stating the team is taking matters into its own hands . It it understood that Red Bull has been investigating of its own accord, using thermal imaging cameras to gain a better understanding of how McLaren is achieving its superior tyre wear. Brown has denied any wrongdoing is taking place, and as ever, did not miss the opportunity to have a laugh at Horner's expense. Nonetheless, the Red Bull team principal saw the funny side of the gag when shown the American's "tire water" by Sky Sports F1 .  After laughing, the 51-year-old jokingly hit back, making light of his team's energy drinks roots by saying: "We'll send him a Red Bull down if he needs some energising."