The late Don Schroeder of CAR and DRIVER, who did the testing of Spindletop, at the Chrysler Proving Grounds, published results from cornering force tests he conducted on Chrysler's 300-foot skidpad.
He took a Corvette of the day, and swapped out all four wheels for space-saver, spare tires ( rubber donuts ).
The Corvette returned almost identical g-ratings, as with the 'wide' OEM rubber.
The explanation had to do with the compounding of the rubber.
And yes, the tires were only rated for 50-mph, and had a tread life of only about 50-miles, but as far as lateral grip, the section width essentially meant nothing.
