I recently had my tires rotated and now experience a significant hum when traveling a speed. It must have something to do with tread wear but I am not sure what. What causes the hum? Is it a problem?
As tires wear, they tend to get noisier and noisier as the tread gets stiffer and stiffer…And yes, sometimes rotation can cause a startling increase in noise levels…
Tyres don’t wear the same on each corner of a car. You now moved them around and you have tyres that have been worn in one corner in a different corner. They may wear in at the new location and stop making the noise or not.
I do suggest that you have them checked at a local INDEPENDENT tyre store. They may be able to determine exactly what is happening. I suggest this because you may have a suspension problem that cause the tyre wear.
It is quite likely you have irregular wear.
Irregular wear is caused by misalignment and aggravated by insufficient inflation pressure and insufficient rotation practices.
My experience says that the published alignment tolerances are too wide. Not the target value, but the allowable deviation from that value. I think it ought to be half of what is published.
Put another way, the alignment should be within the inner half of the spec.
You should be aware that even vehicles that do not have a pull can be out of alignment. There are settings where one out of spec condition is offset by another out of spec condition ? typically camber vs toe.
Also, many alignment techs think that if the factory did not make provisions to make adjustments for the alignment, then they can?t make an adjustment and will declare the vehicle ?OK?. This is totally wrong.
ALL alignment settings are adjustable, but it may require an eccentric bolt, some shims, etc. A GOOD alignment tech will know what to do and the vehicle should leave a shop with ALL the alignment settings close to the nominal.
So get an alignment. That won’t fix the current problem but it will prevent a future occurance. Also rotate your tires more often. - and hope you wear a new (more quiet) wear pattern into the tires.
To all of the good advice posted so far, I want to add a proviso.
Since your car has AWD, it is vitally important that the 4 tires are very closely matched in terms of tread wear.
If the tires have not been rotated on a consistent schedule (Subaru specifies “every 7,500 miles”, but whatever schedule you use, it has to be consistent.), then you will wind up with tread wear that varies considerably in both the amount of wear and the areas of the tread that are worn. And, as was mentioned previously, incorrect wheel alignment will exacerbate the problem.
The result of not adhering to a consistent rotation schedule is excess wear of the AWD mechanism, with resulting repair costs of $700–or more.
I’m Adding This To My List Of Reasons Why I Don’t Have AWD, 4WD, And Why I Don’t Rotate My Tires (Except Rotating Them When The Car Is In Motion, Like On A Beer Run).
I’ve just never needed any of it. I used to rotate tires, but not any more. All this stuff leads to more problems.
This is a sub-list of My List of Things I need like I need Tap-Dance Lessons.
Keep it simple and maintain an even strain. Play golf (walking, of course) and in between take naps.
Have The Wheel Bearings Checked To Be Sure It’s Tires. A Different Tire Position “Set” Could Exacerbate A Bad Bearing. These AWD Subarus Require Too Much Maintenance In My Opinion. Get New Tires And A 4-Wheel Alignment.