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Discussion Starter · #1 · (Edited)
Ok folks I am assuming I did this correctly and if I did not someone can correct me and this can serve to help other members adjust their speedo for their new aftermarket tires. I am currently running the 275/40/20 front and 315/35/20 rears and have a custom tune in the predator. I chose to adjust by sidewall# because tire height can vary depending on tire pressure, the sidewall # is fixed. Note: This can also be done in the quick adjust menu as well! The reason I used the rear tire numbers is that I assumed that the speedo reads the speed from off the rear differential. This process is important because when using aftermarket tires, they will generally offset your speedometer, and actual speed vs the speed that your speedometer shows will be affected and this too can affect the amount of miles you have on your car...Having more or less miles rather than the real Actual Miles
Here goes on the predator:
Go into performance tune
Custom tune
then Select your custom tune from your tuner e.g 069034ag_toon_009
choose that
Select Modify Tune
Select Agree
Select Modify Parameters
From here you can choose 02 config,cooling fans,esp,idle,rev&speed limits, tire size etc
Select Tire Size
You then have the option of by sidewall# or by height
Select sidewall#
It tells you for 1# is tire width
2# is aspect ratio
3# is rim size
You will move along a horizontal bar to select these numbers in all cases so for the first one
1# is tire width scroll to 315 and select
2# is aspect ratio scroll to 35% and select
3# is rim size which should already be at the default 20 inches .....Select the default
Select Apply
It asks Are you sure?.....Obviously select Yes
You are Done :bluecap:
 

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The difference for that combo vs stock is 0.3 inches or about 1% on the rears so your speedo will read less than 1mph off at 75mph. Probably more error than that in the calibration.

Anyway, nice to know how to do it for winter tires or what have you.


Sent from my Autoguide iPhone app
 
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