I know bigger tires will get worse mileage, along with the computer showing incorrect mileage too. proably 1mpg total difference. What are the advantages to getting it changed to the correct diameter? The mileage being off doesn't really bother me. I drive my vehicles into the ground no matter the mileage Lol
You can see in my previous post a 2.1 mph error at 60 mph. That's no biggy provided you always remember, your speedo is not accurate. And when your mind is somewhere in the clouds while you're rushing to an appointment, you always have to remember that error increases with speed. Look at the chart I posted for reference.
Now at 70 or 80 mph, a local cop or state trooper won't care about your speedo accuracy problem, he/she will just right the ticket up and you pay the fine plus the potential increase in insurance costs due to demerit points. If you're confident you will never forget, excellent and good for you.
When I looked to correct my tire size error, Jscan was the least expensive app but if you decide to make changes, you might look at the enormous myriad of changes you can make with AlphaOBD for a few dollars more.
I've had my truck for 1 year and have yet to correct my tire size error. It's on the list and I have some of the parts to make it happen. Mine is much more of a PITA than yours. I have to access the SGW behind the radio and install a bypass cable.
And the bypass cable has to be removed after changes or at least before I visit a dealership when they need OBDII port access.
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