I have a 2009 ex-l. I believe everything is stock. It currently has p225/50r/17 on. I believe p225/45r/17s should be good but I wanted confirmation. One dealer said no problem another said there is a potential for adverse effects.

 

If you switch to 45 series tires then your speedometer and odometers will read high (i.e. a bit faster and log more miles driven than actual). Other than that, no real downside.

 

Shipo has given his correct opinion..