Just had my wheels refurbished as I had a slow puncture. We dunked it in water and it was slowly leaking round the rim. Its not now but i am still losing pressure so i am getting a new tyre (contisport 5 to match the rest) as it was previously repaired although the repair was not leaking. I can only think it may have leaked when the weight of the car was on it. Anyway a new tyre is the only thing left to change, and i have approx 5mm tread left on both rears. Would you change both so they have matching wear or can i get away with just changing the one?