35's changed my shift pattern?

[Old School Joe]

Hi Guys ,
I'm a newbie and was searching old threads but didn't find anything on my problem.
I have a 19 Ram 1500 with the 5.7. and the 8 speed auto. Here's my problem...I put 275/60/20 on bigger than the stock 275/55/20 but not by much and my shift points are higher. It seems quicker off the line but won't go into 8 gear until its above 75 mph. Had it to 2 different dealers to recalibrate shift points but no change. Has anyone else encountered this, any solutions?? Thanks!

 

[Scram1500]

Did you recalibrate the speedometer? Also, the truck has to work harder to turn bigger tires so it makes sense to hang in 7th for a while, specially if you have a 3.21 ratio

 

[Old School Joe]

Did you recalibrate the speedometer? Also, the truck has to work harder to turn bigger tires so it makes sense to hang in 7th for a while, specially if you have a 3.21 ratio

I do have the 321 rear, I can drive for 20 miles on the highway at 75 and it will never upshift. RPM's are high and gas mileage sucks. The dealer recommended a tuner I can't believe that an inch in tire size would warrant that but guess that's why I'm old school! I see plenty of these trucks leveled with 35"s and everyone I ask say they have no issues..I feel like I'm missing something obvious

 

[LaxDfns15]

You're not even on 35's. 275/60R20 is a 33x11 tire. You said you took it to dealers, but did they actually recalibrate the tire size or just flash the transmission? I have 295/70R18's from the stock 275/70R18's, and after I changed the tire size in the truck I didn't have any shifting issues.

 

[Old School Joe]

You're not even on 35's. 275/60R20 is a 33x11 tire. You said you took it to dealers, but did they actually recalibrate the tire size or just flash the transmission? I have 295/70R18's from the stock 275/70R18's, and after I changed the tire size in the truck I didn't have any shifting issues.

I believe they flashed it

 

[Old School Joe]

You're not even on 35's. 275/60R20 is a 33x11 tire. You said you took it to dealers, but did they actually recalibrate the tire size or just flash the transmission? I have 295/70R18's from the stock 275/70R18's, and after I changed the tire size in the truck I didn't have any shifting issues.

Thanks for the correction on the size, I knew it was 1" bigger than stock ...I didn't realize the factory size was so small!

 

[Ready Go]

Your 3.21 gear effectively becomes a 3.10 gear when going from a 275/55R20 to a 275/60R20 tire..that is barely any difference..I suspect you need to use AlfaOBD or Jscan, etc to reprogram the PCM/TCM for tire size/speedometer to get the trans recalibrated back closer to OEM characteristics again.

 

[SD Rebel]

Makes me wonder of all the dealership installed lift kits and 35" tires if they go through the effort to actually reprogram the tire size/speedo and tire pressures? How many of their customers who overpaid for often 3rd party installed kits are running the way they should? If not, many of their owners wouldn't know any different since it was like that since new.

 

[Old School Joe]

Your 3.21 gear effectively becomes a 3.10 gear when going from a 275/55R20 to a 275/60R20 tire..that is barely any difference..I suspect you need to use AlfaOBD or Jscan, etc to reprogram the PCM/TCM for tire size/speedometer to get the trans recalibrated back closer to OEM characteristics again.

thanks for the info, I will look into getting one

 

[Old School Joe]

Makes me wonder of all the dealership installed lift kits and 35" tires if they go through the effort to actually reprogram the tire size/speedo and tire pressures? How many of their customers who overpaid for often 3rd party installed kits are running the way they should? If not, many of their owners wouldn't know any different since it was like that since new.

My local stealership said the install a programmer via the obd port adjust for tires and shifts and throw the programmer in the glove box! I just don't remember the brand name, he did say it was about $500.

 

[Scram1500]

I used a Hypertech around 5 years ago, it's only function besides OBD and body codes diagnostics is tire size adjustment. Should have gone with Alpha or Tazer in retrospect. Currently $230 on Amazon

 

[Old School Joe]

I used a Hypertech around 5 years ago, it's only function besides OBD and body codes diagnostics is tire size adjustment. Should have gone with Alpha or Tazer in retrospect. Currently $230 on Amazon View attachment 201563

TY

 

[moparleo51]

TY

if your in ohio in the northeast, your more than welcome to use my by pass and alfaobd.

 

[2025 Ram Limited]

Maybe a Tazer DT will fix it. And give you more options to boot.

 

[LaxDfns15]

AlfaOBD + a bluetooth OBD II module + the security bypass got me set straight. Takes a little getting used to, but once you can navigate the menus (multiple forum posts on how to use it) you can go pretty quick. I had to change my tire circumference multiple times to get my speedometer right, but once I did my speed is dead on with GPS and a radar gun.

 

[J_Bone]

Hi Guys ,
I'm a newbie and was searching old threads but didn't find anything on my problem.
I have a 19 Ram 1500 with the 5.7. and the 8 speed auto. Here's my problem...I put 275/60/20 on bigger than the stock 275/55/20 but not by much and my shift points are higher. It seems quicker off the line but won't go into 8 gear until its above 75 mph. Had it to 2 different dealers to recalibrate shift points but no change. Has anyone else encountered this, any solutions?? Thanks!

I installed the Tazer to adjust the speed and fold in mirrors when I shut off the engine. It works great and leaves the OBD port open for other diagnostic or other controllers.
After adjusting the speed for my 35’s, my gas mileage and shift points were where they should be.

 

[1923bob]

Tazer works great.

 

[Old School Joe]

if your in ohio in the northeast, your more than welcome to use my by pass and alfaobd.

Thanks but I'm in NY!

 

[1923bob]

I installed the Tazer to adjust the speed and fold in mirrors when I shut off the engine. It works great and leaves the OBD port open for other diagnostic or other controllers.
After adjusting the speed for my 35’s, my gas mileage and shift points were where they should be.

Yep Tazer is cool I used to have my mirrors do that but then we took a trip back to Denver and my passenger mirror froze in the folded position. LOL