Myself and I'm sure many people on here, have questioned what the difference will be in their speedometer if they upgrade to a bigger tire. I found if you go over to Discount Tire Information center (http://www.discounttire.com/dtcs/infoTireMath.do) you can calculate the difference between two sets of tires. Here is the calculation I was testing. Just remember the first set of tires you plug in should be what your stock tire is, otherwise it won't calculate correctly.

 

Here is another site to check out.

https://tiresize.com/calculator/

There is a ton of additional info available including a side by side visual comparison.

 

and just for fun:
http://www.rimsntires.com/specspro.jsp

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