Kurveygirl 83 degree valve stems

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Are these the right stems for a Norge front and rear.  Do the tyres need a rebalance after?

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Those look to be the correct stems, both "arms" need to be of the same diameter which these seem to be.

NOTE: These angled stems are not compatible with the spoked, front wheels on the GRiSO 1200 SE and Stelvio NTX models as the spoke wells are too close to one another to accommodate the wider flanges on this type of valve stem.

You'll need to remove tyres to fit the stems, so a re-balance would be part of the job anyway.