Wheel Spacers/Stock Bearings

[essjayarr]

I'm looking for input from experience with wheel spacers on the rear of IRS cars with stock stub axles and bearings.
I bought my car with 3 1/2" widened fenders. I'm using 16x7 wheels with 37mm et.
I'm considering going too as much as 18mm spacers too fill out the wide fenders.
I've got to decide to use spacers with theses fenders or go to 2 1/4" rear fenders.
The question is, "Will the stock bearings hold up with periodic re-packing?"