Situation: Looking at a 2018 Panamera (sport turismo) It is fitted with the OEM 19" wheels. I would typically be quite happy with the smallest wheel option - not a big fan of ultra low sidewalls for an assortment of reasons but, in this case, the size presents a problem: The tires, F/R are 265/45R19 and 295/40R19. There are very few tires available in these sizes - all high performance summer tires (there may be one dedicated winter tire but, for me, it's a moot point. An apartment dweller, I have no ability to store a set of off-season tires so I need an all season tire. Before someone makes a comment to the effect that if I'm willing to make the compromises involved, I shouldn't be driving a Porsche, I am well versed in the relationships between tread width/sidewall flex and compound and dry/wet/snow traction.
So here is the question: If I drop down 10mm ~0.4" in width to 255/45R19 and 285/40R19 (the OEM tire diameters are 28.4"F and 28.3"R, the alternates are 28.0" F&R) does anyone see a problem?
The alternative is to fit 20" wheels - doable but not without co$t
Thanks for any comments/suggestions

 

The difference is negligible. I've had 245 and 235 on the front of the CTS and couldn't tell the difference. I doubt the contact patch would change that much for 10mm

 

Please PLEASE buy now. Prices are already up and with demand, greed and a rubber shortage (among others) the price is only going up.

 

Thanks - supports my thinking and the variations in contact patch are probably within manufacturer-to-manufacturer differences.

 

I am however going to run a set of spaces on my winter set for my first time. I had some stock wheels I was going to run for snows on my Macan but one rear wheel had a stress crack. I already had the new snow tires so I bought a set of TSW with an offset more appropriate for the Q5. In that scenario I believe that between the AWD and handling concerns getting the setup as close to stock would be beneficial.