Nope, something still not alligning about this. In my mind the dry surface grip levels should not affect the grip balance of a car, I think grip should change proportionally, unless there would be some exact differences in tires rubber compounds and treads. In wet the balance definitely can change because wider tires has more challenge to remove water, as much as I know. Thats interesting. I never heard about, so it is weird if its widely known. I might have missed it. Perhaps by a chance there are any additional real life references to this phenomenon ? Could it also be down to perception ? Oversteer is usually much stronger sensation than understeer, true ? So when grip increases reduced oversteer feels more than proportionally reduced understeer ? Driving style perhaps could be a factor too. So if driver has a tendency to overuse throttle at mid-to-exit before straightening out the car, but never use too much steering input. So in such case driver is always underperforming his front slip angles, and always overperforming rear slip ratios. In such case it makes sense that with increase of grip more improvement would be perceived at rear than at front.