By AJ Design Software
To compare original tire size to replacement use this calculator.


Step 1:  To edit "original" or "upgrade" tire shown:
       Click "original tire" to enter original tire.
       Click "upgrade tire" to enter replacement tire.
Step 2:  Select correct units based on tire size format.

Step 3:  Mouse over "TW" pointer and drag it until the correct "Tire Width" appears.  (First
number in metric tire size)
ex:  205/65 R15

Step 4:  Mouse over "AR" pointer and drag it until the correct "Aspect Ratio" appears.  
(Second number in metric tire size)
ex:  205/65 R15

Step 5:  Mouse over "WD" pointer and drag it until the correct "Wheel Diameter" appears
(Third number in metric tire size normally preceded by an R [Rim diameter])
ex: 205/65 R15

To view results:  
Solution shows the side by side comparison for the original and new tire size entered.

Click on
Graph to see how the new tire size will affect your actual speed vs. speedometer
reading.  Generally, the closer the red and black lines are to each other the better.  If you
mouse over the plot lines on the graph you can see the original tire speed vs. the upgrade
tire speed and speedometer indication.   

205/65 R15 94H
205 = Tire width  
(The tires section width , tread width or overall width. [inches or mm])

65 = Aspect ratio
(The sidewall height of the tire as a percentage of width. Also known as series and profile.)

R15 = Rim diameter

94H = Load and speed rating