Is there a way to calibrate the speedo?

[fordtrux88]

I am looking at installing 31" tires on my 98 ranger and am wondering if there is a way to calibrate my speedometer for the new tires. Does anybody make a kit for bigger tires?

 

[hondaxr650]

A Ford dealer can do it for you. Your speedo gets it's input from the rear ABS sensor, through the ABS module. The module can be reprogrammed for a different size tire. It's input to the module in revolutions per mile, so you'll need to know that info for your new tires.

 

[JohnnyO]

Superlift makes a calibrator but for just going to 31's I wouldn't worry about it. Check your speedo against a GPS or radar speed sign first. My Sport Trac has the stock tire size and the speedo is 3 mph fast at highway speed. So if I put bigger tires on, it would be about correct. Numsayin'?

 

[TwoTrackMind]

I got my 98 with 235/75/15 tires and 3.73 gear ratio. The speedo was about right on. I put 31's on and the speedo read about 4-5 mph low @ 60. When I put 4:10 gears in, the speedo was right again and it had the "get up and go" it used to. I'd recommend a gear change to match the tires. Good excuse 'eh?

 

[4x4junkie]

I got my 98 with 235/75/15 tires and 3.73 gear ratio. The speedo was about right on. I put 31's on and the speedo read about 4-5 mph low @ 60. When I put 4:10 gears in, the speedo was right again and it had the "get up and go" it used to. I'd recommend a gear change to match the tires. Good excuse 'eh?

Did you somehow replace the tone ring for one with more teeth or something too? How does changing the gear ratio change the speedometer on a '98up truck where the tone ring always rotates at wheel speed?

 

[TwoTrackMind]

Oops

Did you somehow replace the tone ring for one with more teeth or something too? How does changing the gear ratio change the speedometer on a '98up truck where the tone ring always rotates at wheel speed?

Now that I think about it, your right. Changing just the gears would NOT fix the speedo. I changed my gear ratio by changing the complete rear axle from a 7.5"rg to a 8.8 from a LevelII Ranger. The tone ring had a different number of teeth and thats what fixed my speedo to match the change in tire size.

I guess I got this confused with my '78 dodge. That one started with 3.23 gears and 235.. tires. When I went to 4:10 and 33" tires the speedo corrected itself. I had forgotten all about the tone rings on the Ranger. Sorry for the confusion

Does the size of the ring gear always determine the number of teeth on the tone ring, or can you get different tone rings for a particular size ring gear?

 

[4x4junkie]

Yeah the swap from a 7.5" to 8.8" is what I suspect did it and you got lucky.

I'm not aware of tone rings being available with different tooth counts. As I understand it, you simply recalibrate the speedo through the PCM on these trucks using a programmer.

 

[06RangerXLT]

superchip tuner

 

[TwoTrackMind]

superchip tuner

Um, I went to find one for '98 and it said "Currently, Superchips Performance Chips products are not offered for your Ford Ranger"

I see '99 is offered. What would be the difference? What about changing the PCM or ECU to '99?

 

[Sasquatch_Ryda]

http://www.superlift.com/accessories/truspeed.asp