Hi all,

So I've had what at least appears to be a tire balance issue with my truck since at least June after I made a 600 mile round trip towing my boat. I feel a vibration starting at about 45 mph all the way up to the max speed I've driven it of 70 mph, in 2wd of course.

I've since done the following in this order:

• Had the tires/wheels rebalanced using a dynamic balancing, but not road-force balanced.
• Replaced the lower ball joints (I did them because they were on the verge of being out of spec and I had the truck in the garage anyway). I also replaced the left front wheel bearing because the sensor was bad, not because the bearing seemed bad.
• Had the tires/wheels rebalanced using a road-force balancing machine. (This cost me $200!)
• Installed balance beads into all four tires.

The vibration might have gotten a bit better after each of the rebalancing but it is still quite noticeable.

After doing some simple math, I worked out that if the tires/wheels were unbalanced then I should expect a vibration of about 10 Hz at about 53 mph and I'm pretty sure that is what I am feeling at the steering wheel. I quantified this by comparing the sensation to eighth notes at about 150 beats per minute. (Yes I was once a band nerd! LOL I also compared it to a metronome app)

The tires are 30x9.5R15s Toyo A/T IIIs on stock aluminum rims that are about 3 years old and have just under 20k miles. The last time they were rotated was about 3,000 to 3,500 miles ago. I noticed that I had some heal-toe wear on what are now the rear tires. This wear appears to be evenly distributed around the whole circumference and on both sides of the tires. (https://blazerforum.com/forum/tires-...ations-107412/)

I have also not noticed any issues with the tires becoming deflated and they all seem to hold pressure fine.

I will be moving the tires from front to back to see if that makes a difference or not. However, since all of them have been balanced, I doubt that will result in a change.

With that in mind, my next thought is that there could be an issue with the lateral (and radial?) runout of my bearings. Since the tires/wheels were balanced on machines, I think it is safe to assume the machines have no runout so that it could be the tires and wheels are fine.

I was thinking that I should measure the run out but I don't have any specs for this in my GM Service Manual. All I have is a check for the runout for the front wheel bearings as measured about 1/2" from the outer edge of the brake rotor. (it is 0.0015" BTW).

I was thinking of checking this at all four rotors using this same spec. If I can, I might also measure the runout at the rims and calculate how much larger the spec should be at that larger radius. (I'm guessing about 2x to 3x larger.)

Can any of you suggest anything I should look for when checking the runout of all my wheel bearings and wheel mounting surfaces? Do you know what the specs should be at the outer edge of the rotors or at the wheel rims?

Can you think of anything else I might check? Is there any flaw in my logic so far? Are A/T tires just always going to vibrate?

I'd rather not get rid of the tires as they should not even be through about half their life at this point.

 

Hi all,

So I did a test of the lateral runout for all four rotors/wheel mounting surfaces. I found the left rear was not within spec, the other three were fine.

I then took the caliper and rotor off to check the lateral runout at the axle shaft flange. Lo and behold, it had a variation of 0.0070". The specification is less than 0.0020". Ugh.

Now I guess I get to learn about replacing rear axle shafts and bearings.

One think I do know is that you better do it outside or in a shop with lots of room to the side so you can pull it out all the way.

 

Good luck Christine. I hope you've found the source of the issue.

 

Thanks. As it turns out just yesterday afternoon I think I found it. My left rear axle flange has excessive lateral runout. At the outer edge of the axle flange it measured 0.007" where the allowed amount is 0.002". This translates to about 0.042" or between 1/32" to 1/16" at the outer edge of the tire.

Now I'm shopping for replacement axles. I have another thread where I ask for advice on how to do the job and what brands I might look for.

 

Well I was able to replace the left rear axle and the vibration is quite reduced. I still have some but I think it is just because of the aggressive tread on the tire.

The job was not too hard, but I had to do it outside since my garage would have been too narrow.

This video was pretty helpful to provide an overview of the part replacement.

The part I got was the Yukon Axle Shaft - 16769 kit from O'Reilly Auto Parts. In addition to the axle, it came with new wheel studs, lug nuts (which were the wrong size), a new bearing, new axle seal, and a differential cover gasket. It listed at the time for $203. There was an identical kit, number 16801 for $321. I called both O'Reilly's and Yukon to confirm that there was no difference to make sure I wasn't missing anything with the more expensive kit. ( I wasn't.)
https://www.oreillyauto.com/detail/c...aft/rrp1/16769

One part of the repair that gave me a bit of a pause for a bit was that when trying to rotate the differential mechanism with the axle could result in the inner part of the carrier rotating a bit relative to the ring gear, so watch out for that. If you do this, you will have to rotate the differential gearing a total of 360 degrees to get the C-clip for the axle out and back in.