9in drum brakes

I see you guys have gone off-Physics again. Maybe since I studied it, Physics seems so common-sense. Yes, "tires stop a car". What do brakes do then? They stop the wheel from rotating relative to the vehicle. Can you skid all 4 tires, and evenly, using your brakes? If so, your brakes can bring the tires to the max stopping ability, which is right before the tires skid.

Why are "big brakes" better then? They have more mass to absorb the braking energy better (less temperature rise) and disk brakes cool off faster, especially those with internal air channels which act like a fan, and even better if air ducts from the grill direct airflow at the rotors (i.e. big ugly black grills begun by Lexus). When does that matter? If the friction material temperature rises until it melts, you get "brake fade". When might that happen? Braking continuously down a long grade, aka clueless Florida drivers on the Blue Ridge Parkway (smell them a mile ahead). Trying to dissipate too much kinetic energy (mass times speed squared). If your 9" drum brakes don't fade when braking from 65 mph, then that is good enough for sane drivers. But, then they need to cool off, so don't keep doing that say in say twisty road-course racing. Use engine-braking on long downhill grades.

Why might drum brakes be worse? Neglect. Touchier about friction factor, due to the self-amplifying effect. Any gummy stuff on the shoes (even leaking glycol fluid) can make them self-jam. Above can make the 4 brakes unbalanced so one tire skids early. The amplifying effect makes them better if you lose power-assist and a weak-legged driver is at the wheel.

What about the data that 72BluNBlu presents? I see different tires in all tests. He has an engineering degree so should know that other factors need to be controlled between comparisons. Sure, your car may have spec'ed 170 ft stopping distance (0 to 60 mph) with the factory skinny bias-ply tires, but it might stop faster with say the kind of sticky tires current Mustangs ship with (95 ft stops). Typical sedans with modern tires stop in about 125 ft, pickup trucks in 150 ft, and sporty cars in <100 ft. Faster specs today may also be due to ABS since I think all they do is jam on the pedal and let ABS pulse the brakes. Interestingly, when the earliest Tesla Model 3 was first tested by Consumer Reports, it gave poor 150 ft stops. Tesla made software changes and it dropped to normal 125 ft. My guess is they fine-tuned the ABS pulse rate, though could have worked with the regen balance too. Why off initially? They had recently softened the suspension due to too-stiff complaints, so perhaps hadn't re-optimized the ABS settings. If you think tires don't matter, consider that tests were run stopping on ice with special snow tires vs All-Season tires and the former stopped in half the distance.