if MPG/MPH is inaccurate after installing larger tires - is my odometer too?

[jhonn236_AZ]

Help me understand this.

My thought process is that:

If by adding larger tires my MPG changes, and the only variable in the Miles Per Gallon calculation is the "Miles" due to the larger tires... does this mean that my actual miles per the odometer are also incorrect?

Same with MPH - according to this forum, the MPH is off by +/- 5mph depending on tire set up - again, the only thing that changes here is the M in the MPH formula because the time is the same.

Based on my logic above, and the fact that the Odometer is used to keep track of the miles - I feel like my odometer could also be inaccurate.

Thoughts? I might be stupid, I probably am, so maybe I'm missing a big elephant in the room, but logically makes sense to me.

I started wondering about this because I've had my Rubicon for less than 7 months, and I installed mopar lift and 35s almost immediately after purchase - this morning my odometer read 10,050... There is no freaaaaaaaaaking way I've driven 10,000+ miles in 7 months.

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[UNC Rubicon]

Yes. It will be off. However, you’ve driven more miles than your odometer reads. Your speedometer and odometer are off roughly 6-7% which means you’ve driven 6-7% farther than your odometer indicates since you installed the 35s.

 

[Swadehead]

It will be off, but as mentioned, the discrepancy will be "in your favor" if you will. So you have actually driven more than your odometer states...

 

[mike_b_81]

Yes, like the others stated you actually put more miles on than indicated. The stock Rubicon tires are about 33”, so if true size, circumference would be 103.67” and going to 35’s, the circumference would be 109.96”. So per revolution of the tire you’re getting 6” more travel.

 

[jhonn236_AZ]

well - bummer...

Thanks for the replies guys!

 

[LeoTheDragon]

well - bummer...

Thanks for the replies guys!

Why bummer?

It's kind of a good thing... favorable for you. Your Jeep has less recorded miles than has actually been put on.

 

[jhonn236_AZ]

Why bummer?

It's kind of a good thing... favorable for you. Your Jeep has less recorded miles than has actually been put on.

bummer because that means that I have, in fact, driven 10,000+ miles in 7 months! Lol

 

[plex]

You can either reprogram your PCM or change your time. To do later, you need drive your Jeep near a black hole, but be careful don't go too close to the event horizon.

 

[LeoTheDragon]

bummer because that means that I have, in fact, driven 10,000+ miles in 7 months! Lol

I still must be misunderstanding. How is that a bad thing?! Hahaha, I'm loving every second I am driving my Jeep - I'm looking for reasons just to drive it around.

I've had my Jeep a little over a month and it's approaching 4k miles.

 

[jhonn236_AZ]

You can either reprogram your PCM or change your time. To do later, you need drive your Jeep near a black hole, but be careful don't go too close to the event horizon.

already a step ahead - I bought my Jeep with a black hole included. The factory installed it on the left side of the Jeep, almost on top of the rear bumper. At least it feels like a black hole...

 

[Swadehead]

If you step up to 40" tires, the mileage actually starts to roll backwards. Facts. Look it up.

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