This might be a wired question, but I have always wondering what is the purpose of having a 16" 17" 18" 19" tires instead of the normal ones that come with the car. Does it make the car faster or stronger? Or is it only there to look good and show off? I'm really wondering since i have a 15" right now and I need to know why people get the bigger rims?

 

you need 16 inch tire for your 16 inch rims
18inch tires for 18 inch rims, 17-17,14-14, vise versa.

it's the diameter of the rims(15=stock diameter for most honda)
the width of the rims also have alot of do with handling/gripping on the road

most of the stock accord rims are 15x6.5
meaning only 6.5 inch of tires is making contact with the road
while 16x7, 17x7 and 18x8.5 have an addition inch or two for grip.

most of the people get bigger rims because it looks good and fill in the gap better when it's lowered.

there's also deep-dish rims(18x10++) for show and Drifting(??)

but most of the time bigger rims=more weight=slower

 

Bigger rims & lower profile tires give the same rolling diameter, for speedometer & odometer. But it's the lower profile tires that have shorter sidewalls, so there's less flex and the tires don't feel as mushy.

You trade overall weight & rotating inertia, for better grip for cornering. But going overboard with 18" & 19" isn't always swift, either.

 

bigger is better.. in my opinion

 

Well your opinion is wrong. Sorry to break it to ya.
http://www.accordinglydone.com/tech.php?ID=20

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4DRPIMPIN &raquo;</TD></TR><TR><TD CLASS="quote">bigger is better.. in my opinion</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4DRPIMPIN &raquo;</TD></TR><TR><TD CLASS="quote">bigger is better.. in my opinion</TD></TR></TABLE>

if you going for the "show" or stunna looks...yeah why not?
performance-lightweight+enough ground contact.