Sorry, I ninja edited that while you were posting.
The source of force is the road. Conventionally, the car leans on the suspension, but look at it the other way around, the car is constant and the road pushes against the suspension. It’s easier to think about the dynamics of just ONE corner of the car at a time.
The center of wheel is the easiest way to do your measurements by when doing the actual math once you’ve accounted for its new total width (if using larger rubber, not just spacers on the original wheel size). In either case, that center is now farther away from the original center (leverage) and probably weighs more too (unsprung weight).
Think of it exaggerated hyperbole style. Put 2 foot spacers on each wheel so the car looks like an F1 car coming down the road at you. But onboard the car, the shocks are still mounted in the same spot, the control arms are the same, etc.
You’ll have better weight transfer, more grip, etc essentially all due to less roll. But in the end it’ll still handle like its using 2 foot spacers off the stock hub and mounting points.
It’s a common misconception with wider tract patch is better handling and while that may seem like a plausible effect of adding rubber width, without proper geometry adjustments it makes things difficult to work with and tune.
Shock travel ratio is one of the most crutial and important tuning aspects to be considered. It’s a balance of wheel travel per inch of shock travel and affect EVERYTHING related. Take an OEM suspension, widen teh track without adjusting shock leverage points and you drastically adjust this ratio. Basics 101 -> Too much ratio and you end up with a spongy car or overheated dampers, too little and your dampening rates throughout the wheel travel suffer and you end up with a twitcy, loss of grip scenario.
By adding wheel width past instant centers you change this ratio. On top of that, you also start changing scrub, ackerman, and tracking ability of the front suspension. It’s not always the best option to pursue. Most OEM cars get away with a little more tire width or adding some spacer because they are so neutral from the factory for dim whit spacey drivers who don’t know their head from their ass behind the wheel/
Oh and Pat Long is 911 god. Ever met him Clark. Nice guy and Stupid knowledable on that chassis. Yes I did read the GRM article and i did discuss all the basics behind that chassis and effectively how to put it through a corner in good order.
Met him twice, both on race days, crazy early in the AM when no one else is in the paddock. One of the cooler drivers to talk to, will sit around and BS about car guy stuff for hours. Bill Auberlen is the same way (obviously). I met him when I was like 9 and that day is probably the single reason I race a BMW.
Back to the part about me driving Mike Ferra’s mint rare 911…
