been searching around the old posts to see if i could find something but no luck yet. anyone know if the dealer can recalibrate the speedo from stock 265/70/17 to a 35x12.5x20. if you've have luck how did you get them to do it. i called one dealer and they said all they could get me to was a 285/70/17. trying to find out before i look at the superchips. thanks.

 

they were able to re-cal mine to 325/60-18's...

 

so i found a website that says 4.13 gears with my 35" tires would get me back to stock trim of 265/70/17 with 3.73's. for those of you who are familiar with all of the gearing ratios and such does this sound right? I'm trying to see if the dealer can do something to get my speedo and tranny right since they tell me they can't set the tire size for me. i'm hoping if they can reprogram the computer to 4.10's that will get my speedo back to close and my shift points.

 

you can pick up a code scanner from autozone o-reily's or where ever for under a banjamin that calibrate your speedo

 

I have 315/70/17 tires on my 06' 2500 and the stock gears are 3.73. So if I buy the above mentioned scanner i can recalibrate by speedo???

Please confirm before a I spend any money...

Thanks..

 

All you have to do is get the revloutions per mile for your specific tire. Most of the manufacturers have them on their websites. Just look up the tire, find the rev's per mile and bring that number to your dealer. They put the number in with the STARscan tool and you're done.

They may charge you, but if it's a decent dealer they won't.

Or you can buy a programmer and do it yourself.

Changing gears has no effect on the speedo, only tire size does.

If you want to see what gears to get with a given tire size, use this. I used to get questions on this all the time and use this for easy reference. Just remember, what ever the math says, you want a gear size lower (numerically higher). Math doesn't take into account the added weight of the tire, increased rolling resistance, increased aerodynamic drag, etc.

Here's the math. Just follow the instructions, it's real easy:

 

I was looking for the scanner tool, is this the one you were refering to?

 

so the dealer tells me they can't use the computer to change ratio size nor can they put in the revs per mile for the tire on an '06.says the only thing they can do is change it to a tire size that is in the computer which is a 285/70/17. actually they told me to look at a superchips to redo my speedo. does this sound right or is the dealer i'm talking to way off base and wrong. ifthe dealer is right then i guess it's time to look at the superchips.

 

They are full of crap. He probably jsut doesn't know how to do it. All he has to do is change the parameter in the computer. When you do it with a Superchips, it jsut askes you the tire size and makes the change. The dealer can put in the specific number and your speedo will be dead on.

 

Can someone provide me with the name or the link of the exactscanner tool I need to calibrate my speedo. Drew mentioned it earlier in the thread but I don't knowwhich one I need. I too am having bad luck with the dealer....