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i2 Tire Size

Post here with any questions regarding the use of the i2 on supported Chevrolet, GMC, Cadillac, Buick, and Pontiac applications.

Moderator: sohfast94

Post Thu Jan 04, 2018 8:06 pm

Posts: 8
I have a 2015 GMC and just changed tire size on my 20" wheels

I went from 275/60/20 to 275/65/20 which increased the diameter just over 1".

I plugged those numbers in on my i2 but my speed is still off compared to my GPS which used to be correct to my speedometer prior to removing the factory tires.

What can I do to correct my speed and my odometer?
Ken Currin
2015 GMC Sierra 1500 SLT All Terrain Z71 4x4
South Hill, VA 23970

Post Fri Jan 05, 2018 8:50 am

Posts: 53232
Location: DiabloSport World Headquarters

you just have to adjust the height up or down to get it to read properly.
Mike Litsch
Powerteq Customer Service Manager
Diablo Tech support by phone:
561-908-0040x4
M-F 8:00 AM to 5:00 PM EST

Post Fri Jan 05, 2018 8:56 am

Posts: 8
mikel wrote:
you just have to adjust the height up or down to get it to read properly.



I picked the option to plug in the actual tire size. There was one for side wall height. How do I go about tweaking this?
Ken Currin
2015 GMC Sierra 1500 SLT All Terrain Z71 4x4
South Hill, VA 23970

Post Fri Jan 05, 2018 9:08 am

Posts: 53232
Location: DiabloSport World Headquarters

you can either adjust the aspect ratio up or down to correct it or use the height in inches option. Start by measuring the height and enter that.
Mike Litsch
Powerteq Customer Service Manager
Diablo Tech support by phone:
561-908-0040x4
M-F 8:00 AM to 5:00 PM EST

Post Fri Jan 05, 2018 9:14 am

Posts: 8
mikel wrote:
you can either adjust the aspect ratio up or down to correct it or use the height in inches option. Start by measuring the height and enter that.



So when you tweak one part of the tuning does it effect the rest of the tuning? Or do you have to make all the changes each time? Ie, I have my AFM turned off and the standard Diablo tune, Speed limiter turned off.

And, who is a good source to talk to and tell them all the things I would like to do or change and have them write the tune and send it to me? I had rather pay for the tune then to screw something up and/or cause poor performance and fuel economy.
Ken Currin
2015 GMC Sierra 1500 SLT All Terrain Z71 4x4
South Hill, VA 23970

Post Fri Jan 05, 2018 10:03 am

Posts: 53232
Location: DiabloSport World Headquarters

if you select the same tune and adjust the tire size the other changes will still be saved and applied.

Check with someone like www.diablewtune.com for a good custom tune source.


Thanks
Mike Litsch
Powerteq Customer Service Manager
Diablo Tech support by phone:
561-908-0040x4
M-F 8:00 AM to 5:00 PM EST


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