tire size

[Duck_Fat]

well i was reading a topic here and I found out 15 inch was stock on 89, but i have 16s, how much fast would i be going at like 50 mph, cuz the condition my car is i am sure they didnt change the speedo

 

[HappyG]

depends on the tire circumference/diameter, not the rim size, same diameter, same speedo reading.

 

[Mustang5L5]

with 16 inch wheels, you should be running a 225/55/16 tire. That would be stock diameter

 

[trbkrb]

Here is a good tire size comparison calculator. All you need is the stock size, 225-60-15, and the new tire size to see what affect, if any, it has on your speedometer:
http://www.miata.net/garage/tirecalc.html