the truck has 35 12.5 tires on it and every time I try and change the diameter it wont let me, what am I doing wrong on this?
the truck has 35 12.5 tires on it and every time I try and change the diameter it wont let me, what am I doing wrong on this?
What do you mean it won't let you?
Are you changing it in the gear tire wizard?
Do you have both the PCM and TCM licensed?? (TCM on the 8 speed is different than the 6 speed)
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
I was trying to. everytime I change it it returns to stock numbers.. yes tcm is licensed
So these all the time no problem... gear tire wizard.. your 35s probably closer to 33s
Email Tunes, [email protected]
96 TA Blown/Stroked, 4L80E/Fab 9
15 C7 A8 H/C 2.3 Blower/PI
14 Gen 5 Viper
Custom Mid Engine chassis, AKA GalBen C
@flamingvert1989 - I just did my tires and had issues with getting this updated. I worked with support thru an email and here are the steps I did:
.....Make sure you have an accurate GPS program to test against. Verify the GPS with a known car that has an accurate speedometer as a baseline to work from.......
1) Pull down a current tune of the ecm/tcm
2) Save the file
3) Save the file again with a new name with a reference on what you are doing
4) Go to Tools>Unit Calculator to open the Unit Calculator
5) Put in your new tire size to get the tire size or use an online tire size tool to get the proper diameter of your tires
6) Go to Edit>Gear/tire wizard to open the wizard
7) Input your calculated tire size and enter in your rear-end gear ratio even if you did not change it. If you don't know your rear-end gear ratio you need to have it or be really close to get the speedometer set right.
8) Click on adjust
9) If you click on the Speedo tab you can see your new VSS Tire Rev per... numbers (if you open or captured this on the tune you just pulled down you should see a difference in this number)
10) Save the current file with the updated VSS numbers
11) Write the tune back to the ecm/tcm with "Entire Write" (Entire Write was recommended by the hptuner tech I was working with)
12) Do a road test
13) Repeat steps 6-12 until you get an accurate speed test
***** You can adjust the tire size as you see needed. As Ben Charles stated your tires are probably smaller than the actual. My tires are 305/40-22 which the calculator says they are 31.6" in diameter. In order to get the speedometer set right I had to make the tire size 30.83"
Good luck...hope this helps....
Can you adjust speedo only without licensing the TCM?
*I realize the trans shifts will not be corrected
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