Ok i got my edge tuner and i put 325X65R18 --- 35X13.50R18 Nitto Terra Grappler on it. The tuner has (mm) and its a 4 digit number. My old tuner i just put in the size of the tires and it adjusted the speedo. Can someone plz convert the numbers to what i need tp fix my speedo plz. dont need tickets
thanks

 

Do you have a manual? It contains the formula.

 

yea look in the book it will have the formula

 

So, you want me to go out to the truck, get my manual, and then do a calulation? LAZY! Ok, if you allow 5% squish, I would enter 2854. LOL

 

You can google the formula to convert inches to mm. I did that once when my manual wasn't handy! Basically convert the inches to mm and then times it by pi. (3.1415) Then you may want to deduct 3-5% for tire squish?

 

I think Bluejay's number is a bit on the high side. I think, accounting for "squish", you might try 2696 mm as a starting point. And, depending on how high you've inflated those tires, it could be as low as around 2669mm.

The actual unloaded diameter of your 325X65R18 tires is 34.63 in.

- Jack