I just noticed that my FC, with stock rims, has 195/60R14's, and OEM size is 185/60R14. What is my speedometer difference?

I seem to be atleast 10mph faster on the gauge.

Is there some variance/difference chart or calculator to see how much speed difference with various tire & wheel sizes?

 

circumference:

195/60 14 = 72.92 inches
185/60 14 = 71.44 inches

For an arbitrary distance, the 195s turn 98% of the stock 185s. Therefore, speedo will read 2% too low. If you are going 100 mph, the speedo will read 98 mph. Hardly a big deal. Your final drive ratio will be slightly higher, slightly slowing acceleration.

Your speedo is reading wrong, and has little to do with your tires.

 

What would be wrong with my speedo? It moves fine when I drive, no skips, jumps, pauses.

 

What makes you think it is reading wrong?

-Max

 

Well last time I drove her, I was in the "slow lane" on I-5 in Seattle, WA and my Speedo was reading about 70.

I know I was not doing 70 at all..the slow lane is usually 50-55.

I wish I had Cruise Control so I can time my speed @ 60mph

 

I knew algebra would bee needed in real life, I am trying to remember algebra from high school...whats the formula to figure out my speed?

Say on the freeway I try to keep at a steady 60mph, I time how long it takes me to get form mile marker to next one...then devide distance with time?