Do I need a programmer?

[AllenTC2]

I decided that I wanted to get new tires/wheels for my Sport S. While digging through mountains of pictures and adds and articles, one nugget I found was that by moving up to 33s, I supposedly throw off my speedometer by 2 mph.

"No problem" sez I. "I can remember that."

But then as I am wont to do, I start thinking about other ramifications. Does this also impact my odometer? What about the TPMS? Where does the "alarm" come from; the tire or the Jeep?

Which leads me to this...do I NEED to get the Tazer thingy? Or maybe just a quick trip to the dealership once the new tires are on?

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[Ruby Clatterbox]

I've got the Tazer and love the options on it. I was kind of iffy about adding something that alters the computer, but so far it's been great. Don't have to disable the ESS everytime I get in to drive, lock the diffs while in 2wd, disconnect the sway bar in 2wd, enable a front camera, change tire size, the list goes on.

 

[AllenTC2]

Well, that is sort of why I doubt I need one. It's a Sport S, I don't think I can even do those things (though I would love to kill the ESS).

 

[SecondTJ]

I decided that I wanted to get new tires/wheels for my Sport S. While digging through mountains of pictures and adds and articles, one nugget I found was that by moving up to 33s, I supposedly throw off my speedometer by 2 mph.

"No problem" sez I. "I can remember that."

But then as I am wont to do, I start thinking about other ramifications. Does this also impact my odometer? What about the TPMS? Where does the "alarm" come from; the tire or the Jeep?

Which leads me to this...do I NEED to get the Tazer thingy? Or maybe just a quick trip to the dealership once the new tires are on?

Yes it impacts the odometer.

Save money and get JScan. It has the same features but significantly cheaper than Tazer.

 

[Headbarcode]

I decided that I wanted to get new tires/wheels for my Sport S. While digging through mountains of pictures and adds and articles, one nugget I found was that by moving up to 33s, I supposedly throw off my speedometer by 2 mph.

"No problem" sez I. "I can remember that."

But then as I am wont to do, I start thinking about other ramifications. Does this also impact my odometer? What about the TPMS? Where does the "alarm" come from; the tire or the Jeep?

Which leads me to this...do I NEED to get the Tazer thingy? Or maybe just a quick trip to the dealership once the new tires are on?

The ZF 8-speed is a learning unit that adapts to your particular driving style. Without being fed correct data, like tire diameter, it cannot properly and efficiently place shift points. So yes, regardless of what you use to do it, the actual diameter needs to be programmed into the Jeep.

 

[aldo98229]

My JL came from the factory with the speedo off.

I got to drive 1,000 miles after picking up my new Sahara. When I checked my speed against those electronic readers police depts deploy on the side of the road, my actual speed consistently was 2 MPH slower than my speedometer reading.

After replacing the factory 32.1 inch tires (255/70R18) with a set of 33.2 inch KO2s (275/70R18), the speedometer is now spot-on.

I have a Tazer and I like it, but I use it for other features —activate the LEDs, disable Weather Alerts, turn off ESS. Haven’t had to use it to recalibrate my speedo.

My advise is: get the tires you want. Then worry if you need to recalibrate the speedo. If you do, Tazer is a great tool; if you don’t, you don’t.

 

[Whaler27]

I decided that I wanted to get new tires/wheels for my Sport S. While digging through mountains of pictures and adds and articles, one nugget I found was that by moving up to 33s, I supposedly throw off my speedometer by 2 mph.

"No problem" sez I. "I can remember that."

But then as I am wont to do, I start thinking about other ramifications. Does this also impact my odometer? What about the TPMS? Where does the "alarm" come from; the tire or the Jeep?

Which leads me to this...do I NEED to get the Tazer thingy? Or maybe just a quick trip to the dealership once the new tires are on?

You’re talking about a whopping 1.5” increase in tire diameter. Others may be more sensitive to related changes than I am, but I doubt I’d be able to tell any difference in any aspect of the Jeep’s performance with a change that small, and I can’t imagine a scenario in which a tiny percentage difference in the speedometer or the odometer would matter either.

I agree with those advocating for the Tazer, but in terms of tire size correction it’s more of a nice-to-have than a need when the change is less than 5%.

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