I had taken in my Accord last week for my regular balance and rotation at a local Goodyear that I had purchased the tires from a while back. The tread depth is now at 5/32 and I was told all looks good for now and not to replace just yet.

I drove took it on a highway drive and it started vibrating at 45 mph or so and got worse when cruising vs accelerating. It was not doing this before the balance and rotation, so I asked that they take a second look.

The took it in and re did the work and it drove better on the highway without the noticeably strong vibration, still a little but they are older tires.

I had to drive on the interstate yesterday and it was pretty badly vibrating from 50-70 mph. The steering wheel had a strong vibration. I took it back today to Goodyear and told them about the vibration and they did a visual and felt the treads around each wheel and said the tires are fine and that the balance and rotation will not make things any better, but to leave it with them tomorrow and they will check for axle problems and such.

It just makes me wonder why would balance and rotation make the ride worse than when it drove fine before I had the service? What other things might be the issue?

 

Incorrectly balanced tires.
Busted balance machine.
Did they use a road force balancer, a typical spin machine, or a troll with a bubble balance?

A weird one that I've encountered. A busted water separator on the air compressor could inject water into the tire. On a spin balancer the tire will balance out fine, however on a road force or while driving the water does not distribute through the tire equally, like on the spin balancer, and will cause a hell of a racket at speed.

 

I took it back the last time and it turns out that a weight had slung off they said which put it 2 oz off. It is now back to riding smoother now!