i'm wondering how much the odo will be affected by switching to 205/50/15 tires versus stock. i know the mileage will increase, but can anyone give me the percentage increase?

example: if it is a 10% increase than i would travel 1100miles versus 1000miles on stock 195/55.

 

http://www.syty.org/old/calculator.html

Will
-who hopes that helps

 

The outer diameter of the 205/50-15 is smaller than the stock 195/55-15. So your odometer will overstate your miles, saying that you went 1000 miles when in fact you went 984 miles. Same thing with your speedometer speed.