I believe that you will find it disappears after awhile.
I have never tried the Karoo Street, but I have had the Karoo 3. They have a similar tread pattern and had a similar noise about the same miles/speed. But with further wear it disappeared.
That said, the Motoz Tractionator GPS tires are nice too and if your looking for an excuse for a quick exit to the Motoz, the whine is as good an excuse as any
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