Seems simple. Ford engineered the truck to fit both a 35" and a 37" tire in the wells based on the stock wheels and tires available overall across those different build packages. The 37 package changed how they fabricate the rear chassis to fit the bigger spare wheel tire within frame that is 37". They most likely contacted fox and received one set of shocks to put on raptor but the set that go with 37" package is dialed in to not flex or compress as easy to not travel as far to avoid unnecessary rubbing and contact. Now if you decide to change the 35 tire/wheel and travel settings on shocks to accommodate a wider tire and/or a wheel that moves out away from stock position they dialed in you may see the bigger wider tire touch things easier even if it doesnt travel as much as the old set-up... may rub under flex depending on use. Certain combinations of wheel/tire, lift, travel specs... changing travel specs may result in continued adjustments to those things to find your spot. One's experience although helpful may be completely subjective to your own depending on use... age of existing suspension, tire pressure, etc. Can rely on someone to tell you how to transition or research and go for it all on your own.