While searching for front Disc rotors for my 2009 Honda Accord EX (4 cyln.), I found two different size, 11.1" and 11.8". Anyone know why there are two different sizes?

one is standard, and the other is deluxe~

perhaps there are regional differences here a canadian one might prefer the larger brakes, tennessee's Honda's are different...it's hard to provide the exact same to everyone...just be glad both sizes are available~

California Catalytic converters are different then all other 48 states...case in point~

Sport, towing and higher powered engines get larger brakes.

Does it matter? You gonna pull your yacht with it? Just put the right size on there and be done.

amen~

V6 comes with larger wheels and larger front brake rotors.

"Does it matter"? It does if you buy the wrong one.