I've been looking at various boldface fonts and notice that almost all of them have numerals and math signs with the same width as the corresponding characters in the regular font--but a couple of high quality fonts I looked at have wider numerals. I assume this consistency of numeral widths is done so that the numerals will line up if they are used in a table where bold and roman are mixed. Any other reason? Is the consistency of width an expected practice? In the bold font I'm working on, I'm concerned that putting all the extra width on the inside of the "8" will make the counters too closed up at small point sizes, and so am leaning towards making the numeral widths slightly different between the bold and regular fonts.

I also assume that there need not be such consistency when dealing with old style numerals, since these are supposed to blend well into a line of letters; letting them be shaped as they look best would seem the way to go. (If the shapes and sidebearings could easily be made consistent, no harm in that of course.)

Any suggestions appreciated.
David