Ok guys I read the article concerning reprogramming your PSOM for proper tire size. The multiplication rate for 15 inch rims is .0135 and for 16 inch rims .015. Anybody have any idea what the rate would be for a 16.5 inch wheel? I'm trying to get my PSOM reprogrammed properly, from what I can tell its only a 4% difference, but its a big bug up my butt and I want it to be accurate. Any help is appreciated guys.

Jeff

 

The conversion constant formula really has nothing to do with the wheel size. The article fails to inform the user why a 16" wheel equipped vehicle requires a different multiplier. The 16" wheel reference implies the vehicle is equipped with a Sterling 10.25/10.5/11.25 rear axle that uses a 120 tooth tone ring versus the 108 tooth tone ring on the Ford 8.8" rear axle (implied 15" wheels). Therefore regardless if you have 16" or 16.5" wheels with a Sterling rear axle the multiplier is the same.

Reference info from Steve83: Ford PSOM info | SuperMotors.net