There were at least four 6-spoke wheels for the model 66 before and during the time of the Singer 99 construction (#2008, 2804, 32588, & 32581; all 6-spoke) and 15282, a 9-spoke, but none of them were associated with the model 99, that I can tell. The 15282 appeared at about the time as the coming of the hand attachment boss (ie, “motor boss”) on the 66. Some of the 6-spoke wheels had a thick rim, but not all. They varied mostly in pulley size. Some had a “light rim” for Drawing Room Cabinets and Cabinet Tables.
The 99 had a hand attachment listed for the 99-1 model that had a #33604 balance wheel, but I haven't ever seen a photo of it. It was surely a spoked wheel, but I don’t know how many spokes. However, by the time that the 99-12 came along, the balance wheel was #33652, of which I've not seen a photo of either, but I suspect that it was a disc wheel. By the time that the model 99-13 came along, it shared the same disc balance wheel, #33672, with the model 66-6 & 66-8. An interesting note is that when the model 99-31 came along, the balance wheel was changed to the “hand wheel”, but it was still #32672.
The 9-spoke wheel (#15282) from a model 66 fits nicely on a model 99, and is probably what was used as a model for the new aftermarket balance wheels that we can get new today. As a matter of fact, that’s the number that they now use for them.
CD in Oklahoma