I was recently asked about tire balancing.
Reasonable question but as always the answer starts off wit "It Depends"
Vibration can be because of a tire/wheel suspension component is out of balance. Vibration can also occur because the tire or tire and wheel assy is not "round". On a small (14' to 16") tire you can see and measure out of round when the tire & wheel are placed on a spin balancer. I have shown that you can "balance" a square cement block
so you need to be sure your tire & wheel assy is "round within at least 0.030"
The person asking the question, said that they had done some research and learned there were three methods. They wanted to understand the advantages of each and which they should use for their Class-A RV.
The basic method is static or "bubble balance". as seen in this video https://youtu.be/hp3ShyNzK84
This static balancing is lower cost but does not provide the best
balance. This method is not usually
done any more by full service tire stores as it only affects the
"static" imbalance and with today's light weight cars the driver is more
likely to feel even a minor imbalance. I once had a car with one front
tire 1/4 oz out of balance and on a very smooth portion of the
interstate on my way home from work I would occasionally got steering
wheel movement. A re-check at the store solved the problem. The car was a
small light weight sports car and it just happened to be sensitive at
that level. My one-ton dually pickup was not sensitive at the two ounce
level on the rear axle.
The next best method would be with the mounted tire on a "spin
balancer", This rotates the wheel and tire at speed and electronically
calculates where to place the weights.
When you buy a new passenger or pick-up truck tire, this is the method they are normally talking about.
But truck/bus size tires can also be balanced using a heavy duty version of this type of machine.
Spin balancers measures the up-down imbalance and the side to side balance and tells the operator how much weight to place on both the inside and the outside of the wheel to counteract forces in both directions.
Finally there would be "On-Vehicle" spin balance this would give the
balance for the tire, wheel and the brake drum and hub of the vehicle
so if the drum was slightly out of balance it would be
included and weights would counter balance all the spinning components.
If you get this type of balancing done it is important to mark the wheel
position on the hub if you ever remove the wheel to check brakes and to
re-mount the wheel in the exact same orientation. A downside to this
method is that it can't be done to tires on drive axles.
Many drivers of Class-A do not balance their tires as they do not
feel the imbalance. Some others always balance the fronts because the
driver & co-pilot are sitting almost on top of the tires. On-vehicle
spin would probably give the best results but this would be for the
front only. Here is a video showing the process on a Corvette
but RV tires would be the same process but with HD bigger equipment.
I see little reason to balance the rear duals on a Class-A as you will
not feel the balance problem unless something was very out of balance.
Some additional info in another post.
https://www.rvtiresafety.net/2011/11/do-you-need-to-balance-your-motor-home.html
BOTTOM LINE
For Class-A I
think you can just take the RV out for a quick test drive on a nice
section of smooth Interstate. If you feel shaking either through the
steering wheel or floorboards then you would go and have the front tires
"on-vehicle spin balanced".
For Class-C and smaller vehicles using 16" diameter LT type tires I would spin balance all six assemblies.
