2nd Gen Non-Engine/Transmission Taller tire Speedometer caliberation

[barbwire]

I went to a 235/85 from the 215/75, and now the speedometer is way off. I had Chrysler tap into the computer, to recalibrate, and I'm not sure, but I think they went the wrong way. Now according to the mile markers along the hwy. I am running ( I think) about 2 tenths or so difference. The way that Chrysler Mech. talked, they cannot match my tire size into the computer calibration anyway. I have yet to talk the local police into clocking me, so I know how far off the speedometer is. Can anyone help out with any suggestions? I would like to go to an even taller tire, But would like to have my speedometer correct. Is there any way to do this?

Thanks

 

[Mundgyver]

http://www.atrol.com/cx_era.htm#era



I just installed one of these in my truck. Went from 265's to 285's My speed ometer is dead on with my GPS. This box will allow you to calibrate to what every you run.

 

[BarryG]

Aren't 235/85's really close in diameter to the 265/75's that can come stock on the truck. If so just have them calibrate to the 265/75 size which they can definitely do and you should be pretty close

 

[barbwire]

Mundgyver; thank you, this looks like the route I'll have to go. Seems odd though that the Dodge computer couldn't have done the same thing, doesn't it. Is this something that you hook up, use once, then stick it in a drawer, and forget about it until the next time you made a change in the ratio? Or do you hook it up, and leave it hooked up?How much did it cost? And if it is something that you thought you would never need again, maybe I could split the cost with you, and use it on mine , then some one else could maybe use it after me, etc,etc.





Barry, my one ton came out with 215s, and apparently, the 3/4 tons came out with 265s. Anyway, big difference, between 215s, and 235s. And much to big a difference for Dodge to correct, I guess.

 

[Mundgyver]

"Mundgyver; thank you, this looks like the route I'll have to go. Seems odd though that the Dodge computer couldn't have done the same thing, doesn't it. Is this something that you hook up, use once, then stick it in a drawer, and forget about it until the next time you made a change in the ratio? Or do you hook it up, and leave it hooked up?How much did it cost? And if it is something that you thought you would never need again, maybe I could split the cost with you, and use it on mine , then some one else could maybe use it after me, etc,etc. "



You will leave it hooked up and it run all the time. If you change to another tire size, all you will have to do is re-compute the ratio from the original tire size to the new size and dial it in. But with that said, it will be easier because you already have it installed.



Cost was around $125 as I remember but you will need to check with the company for current pricing.