ThunderZ28

iTrader: (7)

trying to iron out my ABS communicating with the PCM

I have a 25 inch tall tire up front, and a 28 inch tall tire in the back..
I come up( using the regearing formula ) with a 3.33 gear..

the formula states that I need to put this gear into the PCM..
is this with the 25" tire inputed as well or do I put the 28" tire in the tire selection??

this is the info I get ..

25" Front Tire
807 Revs Per Mile
120404.4 Pulses Per Mile

---------------------------------------
28" Rear Tire
720 Revs Per Mile
107424 Pulses Per Mile

I have the
VSS Pulses Per Mile, and
VSS Pulses Per Rev tables

also
Speedometer Pulses Per Mile, and
ABS Pulses Per Mile tables ( which the abs changes when changing the tire and gear ratio)

which one?

James B.

iTrader: (1)

Convince the PCM that you have 25" tires on the back too. Use the difference between the rear and the front to multiply the gear ratio and then tell it you have that gear. For exaple, if you have 3.73:1 gears, use 3.33:1 - just like you already know. When figuring pulses per mile you can use the actual gear and rear tire size or the front tire size and the calculated offset gear size - they will come out close to the same.


For accuracy I would use the first two decimal places of tire size too.