I get what you're saying about wheel/tire upgrades, some of which can downgrade the vehicle's comfort and forgiveness, for sure. Tires with an aspect ratio of 35 are just not going to ride as compliantly as the old 70 series, period. As for me, I'm old enough to clearly recall what it was like driving on the CN54, the CN36 and the Michelins also. There's no way in the world I would back-date my S4 Spider to tires like that, for any reason.
You are not back dating from the position of compound or build quality. they will be better than pretty much any tyre manufacturer. these tyres are from Pirelli and Michelin.
the why is because on your car 185/70R14 Cinturato CN36 is more suited to the chassis of your car and will handle and ride better.
Because if I'm on a road trip in that car, and the heavens open up in a deluge, I want all the modern tire technology and design under me I can get.
Why? your car will perform better in the wet with a 185/70VR14 Cinturato CN36 than it will on a modern tyre of the size 195/60R14.
Maybe if there was a period tyre available in that size made by one of the best brands, it might be as good. But i don't believe there is one?
A modern design tyre caracss with a fatter foot print will not give you as good wet handling as the CN36 fitted to a light weight rear wheel drive sports car with chassis and suspention from that period. This is a Pirelli, not some cheap rubbish. these are up to date modern rubber compounds that dramatically improve the performance in the wet, from what it used to be in the day. However this compound is presented to the road on a carcass that handles well with your spider.
Your modern car has heeps of adverse camber, stiffer self leveling clever suspension and the front axle has a hole heep of caster over come by clever powersteering. It is the combination of all these features on your modern car that make them able to benefit from the extra grip of a modern low profile tyre with its wide square foot print.
yet at the same time it is all those features that take away the charisma and charm of the modern car.
Maybe; in the wet, importantly in straight line braking a fatter tyre might be better, but only if the compounds are up to the quality of the Pirelli CN36, which i very much doubt.
In the corners in the wet, in your car, CN36 any day of the week.
In a modern car, then a modern tyre would be better. I'm not trying sell you CN36 for your modern Mercedes. Horese for courses.
Now...if I still had my old Giulietta Sprint??? Absolutely yes-- I would have the 155 series 15 inch tires on it, as original, maybe 165mm but no wider. Maybe a modern Vredestein or a Pirelli replica, for all the reasons you describe. I would likely be trailering that car, anyway, on a road trip.
Obviously it would be the Pirelli https://www.longstonetyres.co.uk/pir...ollezione.html
It is a much better tyre. the Pirelli is a genuine period tyre. The Vredestein aren't bad, but they don't look anything like a classic Alfa tyre. and they are not. you would only buy them if they were a load cheaper.