Hi: This car has a milage of 74000 miles. I drive frequently on the freeways and whenever I speedup above 65mph it starts making a whirring sound which increases considerably with any increase in speed. It becomes very loud at 75mph. A mechanic recommended me that its the wheel bearings which is causing the noise.

Please advise me if there is any other reason for the whirring noise. If it is the wheel bearing then why cant I hear the noise at slower speeds?

thnks a lot,
Saurabh