I always thought it was the diameter but I am now wondering if it was the weight of the larger tyres that caused the noticeably poor performance rather than the change in size.
How do those mechanics in the F1 pitstops manage to lift a wheel and tyre as if it weighs nothing ? It's as much as I can do nowadays to lift a Roadster wire wheel + tyre, maybe I'm getting feeble as well as old.....
