The PCM has a minimum rev per mile setting, I recall it is 620 possible.

a 33” is about 640 rev per mile and a 35” is about 604.

if you have Forscan you trick the system by going into the ABS module and reset the Tooth count on the rear tone ring.

the rear ring has 120 teeth and the front has 60, so to keep the pcm happy and make your adjustments by a number divisible by 2.

Fine tune with your rev per mile setting.

Pirate, you lost me on front ring count. My Ex is 2wd. Wouldn’t it only read off the rear diff ring?

I am not that familiar with the front wheels hubs of the RWd but on the 4x4 models the front tone rings are part of the unit bearing.

either way, the rear tone ring is 120 tooth and if fronts have ABS they will be 1/2 the tooth count of the rear.
change the setting by 10% by lowering the count by 12 teeth ...set it to 108.

now the speedo will read 10% lower...

Okay I understand. I’ll try that tomorrow. Need to dig out my windows laptop for Forscan

No, it does nothing for the speedometer inaccuracy. I also have 35” rubber and changing the settings never changed anything.

start with keeping your rev per mile the same but when you set your ring tone down by 10% you can then go lower change the rev per mile to dial the speedo in to the exact reading.

Just keep the ring tone number you select divesable by 2, that way the ABS module can calculate the front and compensate accordingly. At least on the 4x4 Ex the front ring tone gears size is 1/2 of the rear ring tone gear size.
fronts are 60 and rear is 120

so if you set the rear to 10% lower at 108 it will think the fronts are 54.

correct, as long as you do not need a rev per mile that is lower then ( possibly 600 ) the number the PCM will except.

if you did need a lower rev per mile then the pcm will accecpt then changing the ring tone and or rev per mile isn’t the ticket.

perfect, I checked my speedo agains a GPS app on my phone and dialed the rev per mile so it was spot on at 65.
however at 80 mph the speedo is off a couple of mph... likely just the Accuracy of the stepper motor the speedo uses to display on the dash.... I suppose I could use Forscan to check and see what MPH the PCM thinks the vehicle is going but reality is I just want the speedo to indicate a correct speed at typical highway cruising.

I adjusted the tone ring down to 108. I am now only off by 1 MPH at 65 MPH. Close enough for government work. My Ex stock rev per mile Is at 655 per Forscan.