Laminated tire wheel zerk - repair question

[adlertom]

I need to drill out and replace a broken grease zerk on the rear wheel for my rotary cutter. I can't drill straight into the zerk with the laminated tire on the split rim, so I thought that I could simply unbolt and separate the two rim sides from the tire. With the tire out of the way, I could drill straight.

The rim sides don't want to separate easily from the tire however. I'm wondering if I just need to use more "persuasion" or if I'm missing something. Photos attached.

 

[JPRambo]

40 years ago i operated a 15 ft batwing bush hog. I used a 10 lb sledge for the persuasion.