Bottom line up front: Can the computer data be changed to tell the truck it has 3.73 gears rather than 4.10's?<br><br>I installed 315 BFG AT's on my rig. I ran the numbers before I bought the truck and arrived at this conclusion. My truck with 315 BFG's (33.5 diameter actual measured) and 4.10 gears has the exact overall ratio as stock tires (30.5&quot; actual measured) with 3.73 gears. For example at 75 mph in OD I'm running 2250 rpms and a stock truck with 3.73 gears turns 2249. <br><br>My intention was to replace the speedometer gear at the transfer case to correct the speedometer reading as I had done with my 1997 1500. Dealer tells me you can't do that because this model uses an electronic sensor and sends digital info forward to the rest of the computer system. <br><br>So once again I ask, can't I just have the dealer punch into the computer that I just swapped in 3.73 gears and left the tires stock? That would then send correct information to the speedo, trip computer, engine sensors,etc.<br><br>Option two is to use an electronic convertor such as the one offered by Superlift. I contacted them and they tell me they haven't designed one for the '03 yet. I assume that means they haven't tested the old one with this system yet, but they specifically said, &quot;We wouldn't recommend it.&quot;

 

Thanks. Perhaps if I try a different dealership in a larger community.

 

I understand that, but can't a new gear ratio still be entered as specified above to correct &quot;the problem.&quot;

 

Okay, round two. I found a dealer that is willing to make the change. I took it in today and the service guy immediately tried to correct the difference by changing the revs. I told him that wouldn't work but he tried anyway. Sure enough the tire change is too great to correct this way. Once that was out of his system he agreed to try and change the gear ratio. He could not find that as an option on his computer. <br><br>Does anyone know how one actually goes about changing the gear ratio in the computer? <br><br>If I had cracked open the differential and changed the ratio from 4.10 to 3.73 this weekend, there has to be a way for the dealer to teach the onboard computer what the new ratio is.

 

I think you're right Boss Hog. We tried again at the dealership today, no luck. If we try to change the revs the truck resets to the baseline measurement after a test drive.<br><br>At this point I've given up on tricking the onboard computer internally. I went ahead and purchased a Superlift Speed Sensor converter. That should fix the problem by correcting the information being sent from the ABS system to the main computer. <br>