tire size change speedo correction calculator (1 Viewer)

[Devil's Slide Doug]

Tire size speedo correction without gps. Using the calculator so I can program the yellow box.
U.S And Metric Tire Size Information Calculator
The calculator allows you to fudge the numbers on metric tire size value input until you arrive at actual tire size as published in inches. Going from stock Michelin M+S tires (31.3") to Toyo mt (34.9") with stock gears should result in speedo correction of 11.6%. Sound about right?

 

[kidglove13]

How does this correlate to MPG's
Would you add 11%?

 

[Devil's Slide Doug]

Use the % to calculate how many miles you really drove and then do the usual math. 315s on stock gears is approximately 10% which should be easy. But do really want to know? With the tires and other mods it will simply be worse. But you already knew that

 

[kidglove13]

I know it already sucks
I only track it every now and then to make sure everything is good
Just wanted to make sure I had it right
Thought maybe by some chance my math was wrong and my MPG's would get better

11%+/- does sound correct from the last time I checked with a tire calculator