i'm wondering if my MPH is wrong due to the 19x11 on my rear?

 

it depends on the tire size not the wheel size

 

Depends on what size of tire you are running?

 

245/35 front 285/30 rear

 

http://www.miata.net/garage/tirecalc.html

 

yes, your tires are too small

should be 285/35

 

or 325/30/19 haha. there is no perfect answer, just what you want.


btw this is the first wheel thread not ruined by "you know who" by using clever random remarks no one ever understands.

 

I just went with a 18x11 295/30 series tire (ToyoR888) and at first I thought my speedo was way off. Im sure its 3-5mph off but its the softer ride thats making you feel that way. You'll get use to it in a couple days.