Larger tires vs odometer comparison chart?

[Lustmord]

I had a chart bookmarked that showed the odometer vs actual speed with larger tires but can't for the life of me find it, does anybody have anything like that on hand?

- putting 35" on my Rubicon and while I wait for my Tazer I'd like t have an idea of my actual speed in the meantime.

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[Yellow Cake Kid]

π2R

33" tires: 3.14 x 2 x 16.5in = 103.62in
35" tires: 3.14 x 2 x 17.5in = 109.90in

about a 6% difference

Which is to say that when the speedometer says 10mph you are actually traveling 10.6mph, or when you think you are going 100mph you are traveling at 106mph.

70mph will be approximately approximately 74.2mph.

In other words, not a lot of difference.

 

[Jeepsmashin]

Use a GPS app on your phone to give your accurate speed.

I believe my JLUR is showing 3 mph slower on the speedo than what I'm actually going. The faster I go the less accurate the speedo is.

This is with 315/70/17 MT

 

[TheBirdie72]

When your speedo says that you at traveling at full impulse, but in reality you are now moving at warp 1.5…

 

[OldBlue]

HERE'S a speedometer calibration calculator. It might help.

 

[BuyHold]

Assuming no calibration has been performed, the easiest way to mentally adjust is to just take ratio of New Tire Diameter over your Factory Tire Diameter and multiply by dashboard speed.

For example, if you have a Rubicon and have installed 35 inch tires. If your Jeep dashboard says you are going 60mph then 60 x (35/33) is your true speed... So 63.6mph. (this works to same 6% difference @Yellow Cake Kid used in his example).

You don't need Pi or anything like that to do this since the equation reduces to what I described above... New Diameter over OEM Diameter.

 

[Lustmord]

Thanks guys, very helpful!

I'm usually doing 75+ when on the freeway and just don't wish to stand out to the highway patrol until I get the Tazer (smile)

 

[BuyHold]

Thanks guys, very helpful!

I'm usually doing 75+ when on the freeway and just don't wish to stand out to the highway patrol until I get the Tazer (smile)

If your Speedometer says 75 then you will actually be traveling at nearly 80mph with 35s and no recalibration. In LA you would still be slowing traffic behind you down at that speed, no?

 

[J0E]

Just edit https://bt39.com/GearWheelSpeed and compare

 

[2nd 392]

O

If your Speedometer says 75 then you will actually be traveling at nearly 80mph with 35s and no recalibration. In LA you would still be slowing traffic behind you down at that speed, no?

Or you will be crawling in stop and creep LA traffic. But either way-No Tickets.

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