Even a new tyre on a new rim has uneven mass. At speed this shows up as steering vibration, extra suspension wear and patchy tread wear.
We mount the wheel on the balancer, measure the imbalance and correct it with weights. On alloy rims we use stick-on weights so the rim isn't scratched.
Balance your wheels after every tyre swap, after a tyre repair and once a season if you drive a lot on the highway.