Handy tire size calculator
 

This spreadsheet is really handy as it lets you play with profile changes and even plots the wheel offset as a physical chart.

Start by filling out the specs of your stock tires in the left column and that will give you the total diameter of the wheel in Inches.

Then fill out the Proposed fitment column by changing all settings until the total diameter matches or is a close as possible to the Original fitment.

Thanks!

sick