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I have OEM 20" wheels and Michelin Diamaris tires. When I drive the vehicle at around 90 - 95 mph (145 -155 km/h) there is a loud hum or a very slight vibration. Anybody else notice this?

The vibration is so slight I am not sure if it is from the road.

I have apx 2,500 miles (4,000 km) on the vehicle.

oknish

I have factory 18 in wheels and Conti tires and have this maddening vibration which I know is not the road. Trouble is that it is intermittent and I see it at all speeds. I am living with it for now but one of these days, I am going to go the dealer and get it fixed, I hope.

2thfixr

I have the 20" wheels with Michelin Diamaris tires on my Premier Edition GL also and had the same problem. The sound you are hearing is the tires because they are cupping. The sound started around 3-5k miles on mine and only got worse to the point that it was unbearable. Imagine a constant humming like you have a set of super swampers! 2 weeks ago my car rolled 16k miles and I had the tires replaced even though there was about 60-70% tread remaining. The tires were cupped evenly on all 4 tires. They had the same irregular wear across all 4 tires. Usually you only see cupping on the inside or the outside of the tire and only on the rears or only on the fronts. I had it on all 4 tires! The stupid thing is that there are only 2 tires made that fit the 20" PE rims, Continentals and Michelins. As a result, I chose to put a new set of Michelin Diamaris again. I know, sounds stupid but I don't like Continentals because of issues I had with some Sport Contacts on my prev Porsche. The replacement tires were $1850 including alignment!

My advice to you is to make sure that you rotate the tires religiously, probably every 5k miles or so. Since you are already hearing the noise, have them rotated ASAP. Never drive on asphalt with the car in the raised position. I have a feeling it changes the alignment or camber enough that it might contribute to the cupping.

jpeardm

Good advice, my sales guy was emphatic about frequent rotation and low ride height for on road driving as he admitted there are well known premature tire wear problems on the GL's.

cc5731478

Just got back from a road trip from San Diego and cruised at 90+ mph a few times just to see what happened because I read this thread. I didn't experience any weird vibrations or cupping noises. My GL is sitting on 20" Falken rubber and floated very nicely over to SD and back!