How much does tire size change axle ratio

[Norris McCarty]

I’m considering going from 275 65 18 tires to 285 75 17 tires which will be an appropriate 2” increase in tire diameter.
I have 3.73 axles on my FX4 pkg Powerboost.
Is there a formula of sorts that will tell me how much this 2” taller tire will lower(numerically)my axle ratio?

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[KBKEITH]

https://tiresize.com/gear-ratio-calculator/

 

[Blue Beast]

https://tiresize.com/gear-ratio-calculator/

https://www.intercotire.com/tire_size_change_gear_ratio_calculator

 

[Norris McCarty]

Thank you. The 285/75 17s will give me an appropriate 3:54 ratio. Still workable pulling my 5000lb OP15 5-6 times a year. I can certainly use the 1” ground clearance the way I’ll be using the truck.
Then I’ll only have the extra 15lbs/tire weight difference to be concerned about.
There are always trade-offs when you start modifying things!

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