Running on 33s

[boonesmom]

Hi guys, new to the site.
Just bought a 97 Wrangler TJ, it has 33" tire on it.
Does oversize tires throw the speedometer off?
I noticed I was passing everyone on the highway but I was only doing 52 mph.

 

[Rob5589]

Oh yea, a huge amount with 33's. You can swap out the speedo gear in the t/c to correct it. That or everyone was going realllly slow on the hwy

And welcome to the site!

 

[Brantley]

Yes. It'll be off by whatever percentage larger than stock it is. For example, if your stock tire was 29", 29/33 = 12% off, so at 52 you'd be going an actual 59 mph. I don't know what your stock tire size is, but the math should follow a ratio like that, assuming the previous owner didn't calibrate the speedometer.

If you would like to correct the speedo, it requires one part and is a very simple process.

 

[Jerry Bransford]

Here's how to easily and quickly recalibrate your speedometer by snapping in a new speedometer gear... it can be done in just a few minutes with nothing more than a 1/2“ wrench.

https://wranglertjforum.com/threads/speedo-gear-change.83/