I recently bought larger tires 35's for my 1995 dodge ram 2500 4x4 and now it downshifts under random occasions and any elevation makes it downshift. It also has 2 spots that it constantly searches for gear 35-40, and 55-60.

 

Probably needs the speedo recalibrated. Probably the convertor locking and unlocking at 35-40.

 

How do I do that

 

is this on your 00' truck? if so 35's should not bother the 47re. I would just do a fluid change and band adjustment to see if that helps

 

No, he states it's on his 95.

I know they at least used to make a tuner just for speedometer recal. I would guess a dealer could do it as well.

You need a tuner to get into the computer to do it.

 

Sounds like a TPS signal, others here know alot more about this than I do but your trans shouldnt do that at those speeds. My 1995 trans acts the same with stock tires as it does with 35's. The only time my 47RH does strange things is when i hammer it to the floor, then let up a bit. Confuses the hell out of it with a forced downshft then imediete upshift

 

So nothing that's adjustable to tune shifting??

 

do a search on here for TPS adjustment and Band adjustment, I have never touched a TPS outside my WRX subi so very little experence with them on a CTD. Once adjusted correct This should fix your transmissions strange shift points and converter unlocking and re-locking.

 

https://www.dieseltruckresource.com/...nt-t37559.html

 

I have a 94, and adjusting the bands did nothing to stop the hunting. He has changed the calibration some by running bigger tires, but probably not enough to jump to the next tooth size on the speedo gear. My guess would be that he has 3:54's like mine, and is hitting the shift to overdrive at 35-40, and then the lockup at 50 or so. If he hasn't replaced the TPS, that should be done- it will help. The inside cup of the TPS gets worn, so the throttle shaft moves some without changing the sensor.
There is also a service bulletin for the 94-95 47RH's. Mine shifts too soon into overdrive and lockup, and jumps when it does. When it shifts, the RPMS drop below 1000, and it jumps as each cylinder hits. Chrysler has a replacement PCM that changes the shift points for overdrive and lockup. I haven't done it, because it's about $600 to buy it and have it flashed. I just hit the overdrive button until I'm over 50 MPH. The service bulletin is no. 21-04-95.

 

1 other stupid check to keep your palm off of your forehead....trans fluid level and condition. basics first before delving into electronics