I'm cheap, it's hard for me to spend $100 on a grinding wheel, so have been waiting for a deal. This was $52 for an 8" × 1" wheel. The price went up right after I got it. It was very tight on my 5/8" grinder shaft, probably would have gone on, but been difficult to remove. I lapped the bore, removing less than 0.0005". The wheel is nicely plated, I think maybe the slight tightness was some plating applied to a correctly sized bore. I would NOT attempt to ream, or even worse by far- drill the bore. If you have no laps, fine emery around your finger is what you need, and 15 minutes carefully rubbing evenly around both sides of the bore. Any small error in the bore that would produce a slight wobble will be 12.8 times as much wobble at the rim, on an 8" wheel with a 5/8" bore. Radial runout would be the same at the rim & bore, but who wants any at all? I installed it on a new grinder...it vibrated. Not bad..but that stuff annoys me..so fooled around, measuring axial runout near the bore and far away, and radial runout...there was some. But, after re-clocking relative to the grinder, I got it to virtually none, it is very smooth. I think the runout/ vibration was more likely due to the grinder itself. This wheel is heavy...a vibration will be noticed with very little runout. It is worth taking some time to achieve this, and keep in mind that most grinders are not made to high precision, especially the large washers and nut, which are heavy enough to matter. Even with the tight fit on the shaft, an untrue washer applies a force when the nut is tightened, everything flexes a bit, the result is wobble in the very heavy wheel. And vibration. It grinds nicely, I use it mostly for hand sharpening larger drills. Time will tell how long it will last, but I suspect many years at the rate I will use it. Very happy with it.