Quote:
Originally Posted by Taxi645
With the 2017 rules changes (which luckily have been turned back) we also went to much wider tyres. The 2017 care rule changes didn't have the desired effect (as expected). Unfortunately the wider tyres weren't cancelled along with it. In fact with the changes to the 18-inch wheels they have now also grown in diameter from 660mm to 720mm.
Why would narrower, lower diameter wheels and tyres be better:
Narrower:
- Less (unsprung) weight
- Less drag
- Less aero disturbance (also for the following car).
- Narrower car is more room for side to side action.
- Longer braking distances (so more room for overtaking on the brakes).
- More skill required on the throttle.
- Less corners become easily flat
- Better wet tyre performance.
Smaller diameter:
- Less (unsprung) weight
- Less drag
- Less aero disturbance (also for the following car).
- Better cockpit visibility
Why not use the change to the lower side wall to go back to a narrower 16-inch wheel/ 670mm tyre combo which would be much more inline with goals of the 2022 aero changes, would reduce the weight and the size of the cars again and all the other benefits of the narrower rubber (including being more suitable for very wet weather)?
It may not look like a 80's bedroom poster tyre, but otherwise be a much better choice. Missed opportunity in my book.
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The short answer: 725mm rolling diameter & 18" brings F1 tyres into line with Le Mans Hypercar & LMP2 tyres.
The longer answer: Remember that in 1993, the rear tyres were made narrower...
But the front tyres were kept the same size! 
The narrow rear tyres from 1993 to 2016 were always a bit wrong IMO. [Car width was reduced to 2.0m in 1993 which was unfortunate, and then reduced again to 1.8m in 1998 which was even more unfortunate.]
Worse still, grooves were added to reduced the contact area of the tyres from 1998 until 2008 -- far from making the racing better by reducing mechanical grip, the rule change made the racing
worse. Your suggestion that less mechanical grip would increase driver skill, simply wasn't borne out in reality.
The tyres were then scaled equally front-and-rear in 2017 to avoid the vehicles needing to be redesigned significantly. So you ended up with 2017 rears that were about the same size as 1992 rears (perhaps 20mm wider, 405mm vs the historic 385mm), but front tyres that were a
lot wider than 1992 fronts (305mm vs the historic 245mm).
The 2021 regulations are correcting this somewhat -- reducing front tyre section from 305mm to 270mm, albeit not all the way back down to the traditional 245mm front tyre width.
W.r.t. total rolling diameter. I believe Goodyear always used 640mm (or rather the SAE equivalent of 25") for the front tyres, and 660mm (or rather 26") for the rear tyres. I think Bridgestone (joining F1 in '97 IIRC) however used 660mm (the maximum permitted diameter) for
both the front and rear tyres, and this was the case for all F1 tyres until 2016.
In 2017, the Pirelli tyres increased negligibly in rolling diameter from 660mm to 670mm.
Personally, I would not wish F1 cars to return to narrow rear tyres. F1 rear tyres
should be poster worthy!
I do think smaller rolling diameters would make the wide 18" tyres look better (say 640mm front and 680mm rear -- a V8 Supercar tyre is for instance a 680mm rolling diameter on an 18" rim), but F1 teams seem reluctant to design in significant suspension travel that would be required to accommodate such low profile rubber.
After all, the wide 2017 tyres & increased max. car width have
very welcomely made F1 cars back into awe-inspiring wide beasts that corner in a thrilling manner (I say they are
still too narrow at 2.0m, and FIA should go back to the iconic 2.15m maximum car width regulation used from ~1972 to 1992)!
The modern F1 racers are a far cry from the sluggish, lazily cornering cars of 2014, that were quite the disappointment. In some cases, those 2014 cars with narrow tyres & low downforce were up to 10 seconds per lap slower than a modern 2020 F1 or classic 2004 F1 car. Those 2014 cars were
WAY too slow, far from being a driving challenge, they were just boring with commentators like Mark Webber noting that the drivers did not find them sufficiently stimulating, and that the step from F2 (GP2) to F1 was far too easy.