On the other hand, over the past couple of decades, I've noticed a tendency towards narrowing of newer tires compared to what they're replacing, and not just on bicycles. 
The tire size discrepancy could be due to the aspect ratio, maybe they're a little taller.
There shouldn't be much play at all in the diameter of the bolt compared to the diameter of the hole in the fork. The depth of the shoulder area compared to thickness of the fork and rocker assembly is where the trouble usually is. This fork was in really good condition, with the nut bottomed out on the bolt, there is probably 5 to 10 thousands of clearance, I added a little grease in the joint and it articulates nicely with very little slop. Sometimes the shoulder bolts have been replaced or there is slop due to wear. Nylon washers are a good option to tighten up the clearance and still get proper movement in the joint. I have made incorrect shoulder bolts work by trying different combinations of washers and hardware store jamb nuts. The jamb nuts are normally about half of the thickness of a standard nut, so you can lock 2 of them together when you have your clearance set as you want it.
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