Last Saturday (2nd Jan) when driving down with Fiat Linea MJD, I heard a sudden sound similar to a blown tyre air loss for 1-2 seconds. Its like where you release the pressured air (in trucks/buses). But when I checked the tyres they are just fine. I continued the journey for anotter 15-18 kms before reaching home. This happened 3 or 4 times during 30 minutes of driving. Can someone please advice what the indication means and what should I check?