I'm going from 255/70/16 to 305/70/16 tires. I have 3.55 gears in my 2002 F-150 4X4. With the new tires, the gear ratio will now be (aprox.) 3.88.
Do you think it's necessary to re-gear? (I would go to 4.10.)
If I don't, can I expect engine and tranny damage?

 

i think your gear ratio will be more like 3.31 or so than 3.88. i dont think you will suffer damage but you will probably be unhappy with your performance

 

I got those numbers using this web site:

https://www.f150online.com/forums/li...om/4LoCalc.htm

I dunno. How did you figure 3.31, 00F1504x4FL?
Just wondering.

 

When your go to a taller tire, it raises your overall gear ratio, which means numerically (spelling?) lower. So, your 3.55's will be the equalivant of taller gears, like 3.31 or so. You will need lower gears, like 3.73's or 4.11's to get back to the same overall gearing you orginally had. I also went from 255/70's to 33's with 3.55 gears. I didn't notice a difference besides my speedo is now off 5 mph at 60 mph.

 

Using the web site I posted above, the calculator gives you the new gear ratio closest to stock. I had it wrong. Thanks for the help guys.