excuse po sa TS, makikiride-on lang po ako. i also noticed this high pitched humming sound yesterday when i drove long distance my nissan sentra. the sound is noticeable at speeds around 70kph but it happens intermittently especially when i'm running on an asphalt road or a smooth concrete for a long stretch. but when i deccelerate, the sound wanes off. i don't know if it's just me since when i asked my wife and 2 others, they said they haven't noticed anything. but i'm quite sure i seem to be hearing something na parang coming from the rear wheels, or could it just be my wheels? maraming salamt po sa mga magrereply. happy holidays to all.