Just reread my post. I need to do a better job of proof reading them.
Ment to say: Install one weight on the OUTSIDE and one on the INSIDE and bolt them together sandwitching the disc between the weights.
I'm missing something? If a wheel is 10lbs or a 1000lbs it isn't pulling anything down. When you bolt it to the tractor what is it pulling on? Now when the rear comes up it's pulling on the tractor. The deal is not put so much that you bend the axle when you try to get the wheel up.
The difference comes from the nature of fluids which exert there weight in all directions at any given depth equally. Gravity is what is pulling down and the reaction force (from the ground upwards against the tire) has to balance force for force or motion will occur. That is why the math is called statics. The fixed iron weight does exert its weight all the way to the ground through the rim and tire but it's path goes through the hub bearings. the fluid is free to flow around the hub and only exerts its mass on the inside of the tire contact patch. I'm not a teacher so perhaps that is not the most instructive explanation but if you look it up I'm sure you will find I'm right.
So your trying tell me that if i unbolt the wheel from the axle and roll the wheel out of the way with the weights still kept in the upright position on the wheel. That the weights on the wheel are putting load on bearings. There is the possibility in the case where you lift a rear wheel off the ground that you could create a slightly larger moment due to the placement of the weight. But this would be small in terms of what the axle is used to. But normally when the tires in contact with the ground as intended the tire then wheel support both the wheel weights and the tractor. Main difference between tire and wheel weight is the load path through the assembly. Tire ballast is only held up by the tire
Weight in or on the tires or rims have little effect on the bearings. The affect is only from the change in inertia. More weight makes it harder to start and stop rotation, requiring slightly more force. Very small difference,but a difference.
I would add the fill to the tires. The up sidr far out weighs the down.
Any and all weight added to the rim is transferred to the tire, then to the ground.
It can have an effect on the axles and bearings as the tractor is used. But it's NOT pulling down on the wheel bearings, unless one or both rears are off the ground, or are trying to be lifted off the ground.
The ONLY weight on the wheel bearings, is the weight of the tractor and any weight added to the 3 pt hitch.