Aftermarket tires: speedo calibration non-issue, very interesting info and GPS pictures

[vezpa]

Just some interesting observations.

I have an XL AWD Maverick 2.0 with 4k towing package and a 1.5 level kit on the front of my truck. I added semi-aggressive 245 65R17 Cooper Discoverer Tires for the perfect look and stance. These new tires are one inch taller than the factory 225 65R17 Continentals. I put the old and new tires next to each other when I installed them to see the difference in width and diameter and it was very noticeable to the naked eye. The tires now have only 3k miles on them so wear will not factor into my story below.

The stock rear axle ratio on the 4k is 3.81. With these new larger diamter tires the gear ratio now should be 3.68 according to an online gear calculator. This should change the speedometer and throw it off by a slight margin at any speed, getting worse as the speeds increase.

For example at a GPS 38 mph my speedo should be off by 1.36 mph, at a GPS 69 mph my speedo should be off 2.48 mph and at a GPS 78 mph my speedoshould be off 2.8 mph.

Taking these photos wasn't easy as I needed my second work phone to pull this off.

As you can see by the attached photos I took, my speedometer is eerily spot on at ANY speed I go. I have never seen a truer speedometer reading on any other vehicle. The GPS is literally dead on nuts the same at any speed I drive. There really is no good explanation for this with the changes made. Even from the factory you never have an accurate speedometer like this. Neither I nor the shop doing the install did anything to change the speedometer readings or re-calibrate it.

WTF ? Very unexpected results.

And yes that is Factory Cruise on an XL.
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[Wrench77]

What app on your phone are you using? I like the graphics of it.

 

[93nighthawk]

I am sure you did that 3rd pic on purpose. lol.

 

[Jmav2152]

*sees third pic

Nice

 

[Chris_G]

I am sure you did that 3rd pic on purpose. lol.

I thought it was upside down?

 

[rclee]

It would have been interesting to have done the GPS test before and after the tire swap. Now you make me wonder if my speedo is off by a bit from the factory with factory wheels and tires.

Black Helicopter alert! could this be a way of making the MPG look better?

 

[Allen King Jr]

What app on your phone are you using? I like the graphics of it.

The app is Ulysse Speedometer

 

[vezpa]

The app is Ulysse Speedometer. Ive been using it for many years and it really works well and looks good. I paid a few bucks for the upgraded one with no ads. The speeds I used were completely random as it was hard to drive, balance the phone, and zoom in for the pics at the same time.

I wonder if this is why so many of you are claiming to get such better gas mileage than me?

Hmm...

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[Naranjita]

I had similar results on my 245/65-17's. Some people suggested it wasn't possible, or I was stupid. I would only get to 1 MPH off if I was up in the 70 MPH range. And mine is with the 4K rear end.

 

[TE37Mav]

Yea. Noticed similar on mine. Level and 245/70. Up to about 45-50 it’s only off by 1mph and I’ve tried it up to 85 and was only off by 2mph.

 

[olderbudwiser]

Once upon a time most vehicle speedo's were off by about 2%. Is that still true?

 

[Emrod81]

How did you get cruise control on a factory XL?

 

[Mabcim]

How did you get cruise control on a factory XL?

https://www.mavericktruckclub.com/f...n-enabled-cruise-control-xl-models-only.8959/

 

[Emrod81]

https://www.mavericktruckclub.com/f...n-enabled-cruise-control-xl-models-only.8959/

This is not factory cruise control... He specified that he as "factory cruise control" so that applied the truck has it when he comes out of the assembly line... I want to know how he as it since is not offer on XL model even if you take the Co-Pilot 360 option.

 

[Dawgonit]

I had a jeep wrangler that I put on 1" bigger tires and that made that speedo exactly correct as well.

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