How tight should tenon fit in wheel?
Tight enough to not move or rattle.
The spokes should not click when you are driving, too.
Very tight. You should have to pound or press it in place. Maybe a bit less tight if you have wood felloes as you wouldn't want to split the felloe. (I assume you mean where the tenon fits into the felloe?)
if you are installing into a steel felloe you may wish to build a spoke press
go to the above link in the lower box select wheel assembly spoke press plans (2nd from bottom)
Thanks what I thought,looks like I'll be doing some wheel respoking!
If it ain't tight, it ain't right.