Lol it was a general quote more than a scientific fact but generally a lighter wheel would respond quicker than a heavier one no? All comes down to wheel weight i guess, im sure you could get 19s that weigh less than a certain make of 18s in which case go for 19s but all depends on someone's budget and end goals, i would say my old jdm 17s were easier to go round corners than my current rota 18s though have more traction,grip and feel more planted than the 17s