I tested (both at Michelin and with BMW Motorsport) a range of wheel diameters on cars such as the E34 M5 and others and the technical guys and drivers always agreed on these results. The best mount we ever had on these cars was 235/45R17 all around (by the way, the other fad of mounting bigger tires in the back is another common misconception I will write about in the future if there is interest).
Of course that's when the marketing people came in and said we need bigger wheels, and also wider tires in the back... but everybody knew that when we departed from these optimal values, customers would pay more for a lesser result.
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