The Thorobred lense is a tire company glass insert that was a part of a porcelain neon sign. It should measure an odd size - maybe 17-1/4" in diameter as I recall.
We found several lenses and could never identify the company history for a long time. The guy that sold them to me had picked them up many years earlier while living in Golden, Colorado. I checked the local historical society, etc, with no luck.
Then about a year or so later, I purchased a vertical tire sign with the identical image, and also had received a photo from another collector, showing the sign these inserts were used on.
Earlier, we had a few metal bodies specially made to accomodate the lenses. As John Donahue is a Michigan area friend of yours, and also one of the people who purchased one of the Thorobred's from me, was this his? I thought he bought a single lense in body, at the time - might be mistaken though.
As I recall, all the lenses were near mint, and they make an excellent display piece, providing you have the extra height on the shelf.
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Ron Bettin
740-774-OHIO(6446)
bettin@bright.net