I have not come across speed ratings for cycle tyres, (used to see them for motorcycle tyres.)
Years ago made 60 mph Skipton way on DF. I geuss one could go faster on a bent.
The tyre question flashed through my mind at the time.
No doute the tyre being balance is highly relavant, and if it were not, one woukd obviously feel the vibration.
I'm much more confident on the QNT than the B1, the thought of harm does not pop up on the former, but does on the later!
I'm with you Mark; I don't really mind what number the GPS say, its the flow from the demanded total absorption, that I find uplifting
Be well, bent brother

. (It was 'the Americans' who came up with that term was it not? Not complaining, maybe it fits with the needed ease at daring not to totally conform to Mr/ Ms average.)
Oh, and Mark, I found the addition of front suspension to the QNT luxurious on my broken body; maybe there is a therpeutic need?