I made a 911 1978 Turbo from a Arii 1/24 Kit. Fits perfectly with 94mm.
Offset is maximum front & rear (standard alloy rims from 3racing I guess)
To get the correct wheel size, one have to find slotcar rims with 15mm diameter and 0 or better minus offset. Use a alloy tube to get the width wich was something about 15-17mm for the rear wheels!
Mini-Z rims & wheels will never really look O.K. on those cars.
Rims are too big, wheels are to thin and the width is a joke