Hi.
Yes, they are the original General tires, but the slightly larger size: Mine are 5.30/4.50 - 6 which were standard on the BC1300 which, I believe are 1” larger in diameter than yours which, I believe, were standard on the BC1200.
The tires sizes are noted on the period Bonanza specifications and they note that the BC1300 sits 1” taller than the 1200.
When I separated the wheel halves it was the first time in 52 years the inner tubes had been the light of day. Both inner tubes hold air perfectly and are made of nice thick rubber - much better than what could be bought today. I bought the Bonanza a few years ago and, although, it was missing some key original parts I’m glad it came with the original wheels and tires.
the tires are also 52 years old but are fine for putting around.
Do you have a Bonanza project going?
Regards,