[Farmall] Sheared & rusted out lug bolts...

[Greg Holmes]

My super A has sheared several wheel bolts flush with the hub. A couple others have rusted to the point of requiring re-tapping.
 
I'm going to need the sheared bolts professionally removed. Whatever they're made of, they're trashing my best drill bits.
 
I presume I will need to oversize the new holes a bit. Any recommendations on what to use as a replacement for this type of application?
 
I was down to 3 bolts/wheel, which is fine for light mowing, but I sheared another the other day and I need to find a permanent solution.

Thanks

Greg