Originally Posted by RLSmith
I went from stock Goodyear 225/75 16 to bf Goodrich 255/75 17. What do I need to do to the gears and speedometer? And what is the typical cost for something like this?
You basically went from 29 to 32.
My 2012 JK had the 24s package stock, 3.21 with 255/75-17. I added front bumper with winch, 4" lift, and 35 tires. I ran with 3.21 for a while, even off-roading some tough trails and performed fine. I did use the pro-cal due to the 35 tires.
However I since did regear to 4.88 for a better crawl ratio. It is great Offroading and on pavement. The JK will run at a higher rpm with this combo.
In any case do not count on better mpg. I only get around 13mpg on average.
You should run with it as is and see how it feels. Once you start doing some of the bigger mods you can start thinking about some of the more technical issues.
I hope this helps.