Rear wheel question on 78GL

I put a sidecar on my 1978 GL1000. It has the stock Comstar wheels. When I was out for a ride today and heard (as best as I can explain) a crunching or clicking sound in a turn. It will do it at an idle in a tight turn either direction or at speed in a corner.
The rear wheel was off not too long ago and the bearings felt fine but I know they can go bad fast.
This seems, and sounds more like the wheel is flexing.
Visual inspection of the rivets shows no movement but the noise is there.
Any suggestions??????????/

Thanks in advance

Dan A.
Danbury CT