After the last preparation for Thursday's tractor tour, I made a final test run this evening.
Suddenly I heard a cracking/squeaking sound from the rear wheel/axle during driving.
Lately I mounted wheel weights, so I thought the bolts were fastened too tight.
But then again, that wouldn't make a noise during driving? I didn't see any cracks in the weights from the outside.
My next bet is a broken bearing.
The seal/gasket on the right wheel has been leaking since I have the tractor (6 years).
I have been using my tractor for some sand moving (about 750 kg/1650 lbs) with my rear loading bucket a few weeks ago, so I guess the bearing was already
weak and broke during that job?
Do you have any other thoughts about this issue?
Should replace the bearing on the left wheel as well?
I guess it's better not to drive 80 miles with my tractor at this stage?
, But does your tractor have rear wheels with movable dishes/ centers.( not the fixed type for 14x30 tyres) I have seen the outer lug bolts on these come a little slack in the past and that could cause a cracking or other type noise as the wheel turns and the weight shifts on the center 
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Dandy Dave!
. The last one I did the fronts had been so loose the lugs where worn 1/4" into the dish 
.