Anyone ever have a bad tire.

[grabntwist]

I drive a Mercedes ML sport ute. I recently have been expiriencing a "harmonic hum" between 20mph and 45mph that evetually diminishes as a drive for a while. Heres how far Ive gotten as far as trouble shooting the problem:

The sound is directly related to the rotation of the wheels/axles.. The car makes this noise on cold tires and it goes away after a few miles. This makes it hard to trouble shoot.

A bad differential/CV-joint would make the noise all the time.

If a bearing was bad it would just burn up and continue making noise until failure. A bad wheel bearing would change sound/pitch when you weaved the car left to right.

If it were related to the brake rotors the noise would/should go away once you hit the brakes.

The noise is still there when I shift to "n" while rolling, even with the car off.

It seems when the tires have warmed up a bit usually a few miles it goes away.

The car is pretty new and well maintained. Other than the noise the car runs great. The tires have about 20k on them and show good thread. I have had the car at speeds over 100mph on cruise for sustained distances. This makes me think that the tires a wadded.

I have an appointment at the stealership to get down to the bottom of it, but I just wanted to see what you guys thought. And yea, I know this is a Busa forum but anyone that knows bikes knows cars.

 

[tbonebusa]

How often do you rotate the tires? Seems to me that they would be a logical choice for the hum, too.

 

[da busa guy]

i work at a linc-mercury dealer,we have had some cars and suvs with tires(don't remember the brand ) that would develope kind of a short term flat spot after sitting overnight that would go away after a few miles of driving and the tires heat up.

 

[xzvs]

need to know how many miles and if you rotate tires at every oil change (front to rear)
the front tires tend to cup slightly and will hum (worse on trucks and suv's) -- when the tires warm up it will diminish
thats what I would look at 1st
AWD models use a viscous coupler that can make weird noises too-- on those you have to change all 4 tires at once as even a minute difference (wear) will overheat the coupler

 

[tbonebusa]

the front tires tend to cup slightly and will hum (worse on trucks and suv's) -- when the tires warm up it will diminish
thats what I would look at 1st

that's exactly what happens on my F150 with the 20's on it now....if i don't rotate every 5K or so, I notice some noise and harmonic vibes. I'd do a quick rotate and see if the problem disappears....

 

[Bergster]

I had a truck that did that when it sat overnight. I normaly took about 10 or 15 minutes to smooth out. It only did it in cold weather. It was the tires because the when I changed them It never did it again.

 

[grabntwist]

I normally rotate the tires every 5k @ my oil service. The dealer forgot last time and its been about 10k since last rotation.

xzvs, I believe my truck is 4wd due to it's low range function, although since these new damn car manufacturers come out with so many different terms for 4wd I could be wrong.

Berg, you described it to a tee, and yes it is worse in dry colder weather. Im getting them rotated on Friday hopefully it'll cure the problem. Thanks alot peeps.

 

[xzvs]

yeah it can get confusing 4wd and AWD are basically the same except on some 4wd systems you can operate in 2 wheel only (those models can only be operated in 4 wheel mode on loose surfaces). AWD (aka fulltime 4wd) cannot be overidden to 2wd mode and operates on all surfaces. This uses a coupler that can slip to allow the vehicle to turn. So, if you change say only your front tires and the rears are worn, the rear axle turns faster all the time -- slipping the coupler all the time and will overheat it. Likewise if you change rubber on one side only you will overheat the differentials causing chatter. Even tire wear and correct tire pressures are essential on awd. (14 years with jeep/ eagle - so I had to deal with the talons too)

 

[vman1300]

If your ML has a full size spare, you can swap out one at a time to see if it is a single tire.

I have to do the same thing on the wifes BMW earlier this year.

 

[badboysbailagnt]

if there goodyears thats your problem go with michelin

 

[nitrousjunkie]

Check your tire pressure as well,Your tires lose 2lbs of pressure with 10 degrees drop in temp.Sounds like they sit with low air pressure lets say overnight,and develope a flat spot that sort of evens out as tire pressure is slowly built up when driving.Put 40-42 lbs in them before you go home one night and see what happens the next morning when you leave.

 

[DNGrumpy]

I had one "bum" tire out of four a few years back. I bought GENERAL Grabbers AT's in 33x12.5/15's for and old winter beater truck I had. One of the tires had to be replaced after about 25 miles, it slipped a band. But that didn't go away and was more like a shudder than than a hum...

Ohh and GENERAL would not cover it, their warranty excludes anything mounted on a vehicle for which it was not original equiptment. F-Them, I made the biggest scene at NTB, I am surpised I didn't get arrested...

 

[grabntwist]

 F-Them, I made the biggest scene at NTB, I am surpised I didn't get arrested...

I guess thats why they call you DNGrumpy around here! LOL!

 

[BA BUSA]

I would check your air pressure, rotate, and check that they are wearing evenly