I have some old records of my 1985 Z/28 running stock class autocross.
We used Yokohama A008R tires, shaved to 4/32" tread depth, Koni shocks, hollow Trans Am front sway bar which was later used on the IROC models.
All else was stock including engine, springs, rear bar, bushings, wheels, steering etc.
Just 225x50x15" A008R tires, front sway bar and shocks were done.
The cornering G force was measured at 1.03 G's.
I later ran an 89 IROC in stock class that had larger tires with same setup that was probably higher G force. Tires were A008R 255X50X16 on an 8" wide rim.
David
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67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer