TAZER -- shift points and adding bigger tires?

[NoDegree0311]

You'll need something to tell the computer the new gear size. Tazer will do that although there are other options.

Yea once i do my regear ill enter in those new #s on the taser

I’m just in the process of doing the same thing.
Good to know. Thanks
How did you MPG change?
Not that it’s going to stop me but was curious.

cheers

went from around 20mpg to 15. If you don’t install the tazer to adjust shift points for your new tire size the mpg is probably even worse like 12

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[GATORB8]

Yea once i do my regear ill enter in those new #s on the taser

went from around 20mpg to 15. If you don’t install the tazer to adjust shift points for your new tire size the mpg is probably even worse like 12

It's not really the shift points. Your speedometer/odometer is off if you don't correct the tire size.

EDIT: As an example, for ease of math let's say your going from a 30" to a 33".

Circumference is pi*diameter. So the circumference increases approx 10% just like the diameter.

That means when your speedo shows 30 mph, you're actually going 33. 70, you're actually going 77. And when your trip odometer shows you went 200 miles, you actually went 220.

Since you use those miles to calculate mpg. Your (or the computer's) mpg calculation is also 10% off.

 

[Hoppy Toad]

Hey everyone. Looking for knowledge from people who have the tazer in their Jeep. I have a 21 sport altitude with 3.5” lift and 37s on stock 3.45 gears (for now). Obviously my shift points are a lot higher from the tires and the vehicle won’t go into 7th or 8th gear on its own anymore so i bought a tazer to let my jeeps computer know it has 37s and could adjust its timing accordingly. After install and setting it up, i noticed at lower speeds below 50 my jeep would shift easy and feel good like it did when it was stock. But at highway speeds she still doesn’t like to go past 6th gear on her own. So i guess my question is those who have the tazer jl what’s your experience with shift points and adding bigger tires on there? Will my jeep shift like a stock wrangler if i have the tazer PLUS a regear? Or if i have a regear do i really need the tazer?

You need to regear, and for 37" you need at least 4.88. When I went to 35" my mechanic recommended 4.88 in case I wanted to go to 37" Google gear ratios and tire size for wranglers, stick and auto

 

[Hoppy Toad]

My mpg dropped to about 16 mpg from about 18. These tires are Mickey thompson Baha Boss mud terrain E rated tires. Also, I'm running 26 PSI to get full tread contact.

If your tire isn't as aggressive, then maybe you will not lose so much mpg as I have. And of course this depends on if you decide to run reduced tire air pressure like I am.

After going from 33" to 35" K02 at 30psi, 4.88 gearing mpg went from 17 to 14-15mpg. 2020 JL V6 Auto. Stubby bumper and Zeon winch didn't help either.

 

[Wowowee]

Have 35s, 2021 Sahara 3.45 gear. Hardly see 8th gear, sometimes when downhill or flat road I’ll see 8th.. mostly 7th top gear, one day I’ll regear..
Also have tazer for speedometer correction and other goodies..

 

[Carolina Jeeper]

After going from 33" to 35" K02 at 30psi, 4.88 gearing mpg went from 17 to 14-15mpg. 2020 JL V6 Auto. Stubby bumper and Zeon winch didn't help either.

That extra weight does play a part. Lots of added weight on mine too. I have a Barricade HD front bumper with a winch, a LOD Destroyer rear bumper and the Rusty's heavy duty steel tailgate reinforcement kit. I also installed the full size dual battery kit by Genesis.

 

[bcupton]

Just like everyone has stated REGEAR before you destroy your transmission. I re-geared after installing 35s. That was the single best upgrade I ever had done!

 

[GMONEY]

Yup 3.45s on 37s will do exactly what you are describing. If you had 4.10s it would be a stretch to keep them but yea you need a regear bad.

Yeah I'm running 37s on 4.10s right now. Not ideal but it's not killing me. Likely bumpin up to 4.88s here in a few months.

 

[ejewels]

It's not really the shift points. Your speedometer/odometer is off if you don't correct the tire size.

EDIT: As an example, for ease of math let's say your going from a 30" to a 33".

Circumference is pi*diameter. So the circumference increases approx 10% just like the diameter.

That means when your speedo shows 30 mph, you're actually going 33. 70, you're actually going 77. And when your trip odometer shows you went 200 miles, you actually went 220.

Since you use those miles to calculate mpg. Your (or the computer's) mpg calculation is also 10% off.

I thought it does affect the shifting points on an auto? As they "learn" the new tire size and factor that in when making the calculations and when to shift.

 

[GATORB8]

I thought it does affect the shifting points on an auto? As they "learn" the new tire size and factor that in when making the calculations and when to shift.

I don't doubt the TCM makes adjustments as it re-learns. But the Tazer isn't directly making adjustments like say a Superchips would.

 

[ejewels]

I don't doubt the TCM makes adjustments as it re-learns. But the Tazer isn't directly making adjustments like say a Superchips would.

Oh I didn’t know you could actually adjust (manually) shift points in superchips

 

[GATORB8]

Oh I didn’t know you could actually adjust (manually) shift points in superchips

Haven't used on on the Jeep, but using one on a prior F150 there were a couple shift point options.

 

[RancherRob]

I've got a 2019 JLRU. It's got lots of added weight like a rock krawler 3.5" lift, metal cloak, the front bumper and winch. I upgraded to Goodyear wrangler Kevlar MT/S at 64lbs ea on the stock 4.1 gearing and it ran just fine. I didn't notice any difference in shifting.
However, I felt like I needed a little more off road clearance so upgraded to Nitto Mudgrapplers 37x13.5R17 at 97lbs each and added a heavy duty spare carrier and hinge and falcon SP2 3.3 shocks. But the tires rubbed at times so then I also installed wheel 1.75" front spacers
Now, on the street, my jeep shifts really poorly. Takes waaay too long to shift up and feels like its causing a lot of necessary wear. Going up hills is awful feeling.
A couple additional minor problems are:
1. the automagic car wash won't let me in anymore (they say its too wide)
2. My wife doesn't like that it casts large rooster tails when on the wet roads whereever it goes when raining which is half the year here. She says it throws dirty water all over the cars behind her.

I believe the re-gearing would probably fix the shifting but, I think these rigs just are under engineered & under powered for the large heavy tires and I've decided I'm going back to 35x12.5 tires. If anyone wants 1/3rd worn with only a few thousand miles great tires, let me know.

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