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-   -   Changing registered tire size with DS inTune (

patricklee85 06-09-2013 11:32 PM

Changing registered tire size with DS inTune
First off, I apologize if this isn't the right spot for this.

I have an 09 1500 that came with factory 20's. After leveling kit, I put 285/65/20's on factory rims. I just recently got the DS inTune and starting playing with it. I put the new tire size in but my speedometer is still off, but in the opposite direction. I tried using the metric size and also the standard equivalent.

Before Tune: 55mph on speedo = 58mph in reality
After Tune: 55mph on speedo = 52mph in reality

My "reality" is based on a HUD app on my iPhone. Did I do something wrong with the tuner? Has anyone else what this problem?

mattman13 06-10-2013 10:34 AM

Its well known that diablos tire size programming can be a little squirrelly. Take a tape measure and measure the actual diameter of the tires with weight and squatted and use that in the diameter area. Or trial and error. Lower the diameter in increments until its dead on. My 37s are correct with the tuner programming my truck for 35.5.

patricklee85 06-10-2013 10:39 AM

Ok, I'll try playing around with it. Maybe being as it seems like it was almost a dead on 180 in the reading I'll go with a size right in the middle. Factory is approx 33s and I put on approx 35s so maybe start with 34s and see what that does. Thanks for the input, glad to know I'm not a complete moron.

mattman13 06-10-2013 11:37 AM

Yes I had to play with it a lot. Its definitely not you the tuners great but has its bugs. My 35x12.50x20s were dead nuts on speedo confirmed by GPS when I put the size in the tuner as 33.5 if that helps.

patricklee85 06-10-2013 11:43 AM

Yeah, that helps. At least gives me a place to start. Thanks!

patricklee85 06-10-2013 02:10 PM

*UPDATE* Over my lunch break, I changed the tuner setting to 34in tires. Using the HUD app, it put me right within 1mph. I don't think I'm going to get any closer to that. And that might even be inaccuracy from a free iPhone app, but at least its a lot closer than it was. Thanks for your help!

mattman13 06-10-2013 02:15 PM

No problem at all. Glad you got it figured out!

fastNugly @ BP 06-11-2013 12:19 AM

Always tell members to measure their tire with a tape measure and enter that number in. You'll be as accurate as you can be
Glad you figured it out :smileup:

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