My '99 230 has been developing a buzzing sound from the front end that increases pitch as I go faster. It sounds a little like a big chunky truck tire as it rolls, but not as loud.
I have ruled out the tires though because it is the same when I swap the tires side to side and even when I had a different set of tires. It seems to get momentarily louder when the suspension unloads after going over a bump or a crest in the road.
I have also checked the wheel bearings for wear and play and found neither.

Anyone have a similar issue? Thanks.