Javdog

Need some help SCT X3 Tuner model #3015, I need help with the options in the tuner I loaded a 91 tune and tried to change some of the options like wheel size it asks for revs and not wheels size how do adjust for 20" wheels, here are some of the changes that can be made any help on what to enter would be greatly appreciated, I have a Magnaflow full system with H pipe and BBK CAI and 3.55 gears here are the options in the tuner:
* WOT Fuel Adjustment
• Idle RPM
• Spark Adjustment
• Transmission Shift Points
• Axle Ratio
• Fuel Injector Size
• Tire Size - Rev / Mile
• Air Intake Selection
• Cooling Fan Temps
• Traction Control On / Off
• Rev / Speed Limiters
• Two StepOn / Off RPM

Thanks for any help,
Javier

bonestang

If it is asking for revolutions per mile you will need to calculate how many revolutions your tire will go through in 1 mile (5280 ft). Hopefully you like math as much as I do.

Use your tire size (or manufacturer's data, or tape measure, not sure what would be the most accurate) to find out tire height (same as tire diameter). Multiply the tire diameter by 3.14159 (pi) to find out how far you will move in 1 revolution (make sure to use the same units, preferably inches).

Now divide 1 mile (5280ft or 63360in) by how far you will move in 1 revolution (number from previous paragraph). This is your revolutions / mile.

Ex. 30 in diameter tire: 30in * 3.14159 = 94.2477 in / rev

63360in divided by 94.2477in / rev = 672.27 rev / mile

Read the X3's documentation online to make sure this is what it is asking for. I have not used this feature of my X3 yet so I'm not 100% sure.

As for the gears, are they the stock gears from the factory or did you have them installed? If they are from the factory I don't think you need to adjust the gear section.

duckbubbles

Go to tirerack.com. Find the manufacturer of your tires and look at the specifications page to find the exact tire you have. It will list the revs per mile of that tire and you can put that into the tuner to the nearest 5 revs. (the easiest way to do it)

Frank

Javdog

Here is a link that someone on another forum suggested and it worked pretty well.
http://www.discounttiredirect.com/di...foTireMath.jsp