285/70/17 on stock JL Willy 2021 problems?

[Willywong]

Hey guys so I have a 2021 Jl Willy and I wanted to upgrade the look with tires. My car came stock with 255/75/17 and I was doing my research on here on how a stock Willy would handle 285/70/17 and everyone said it was perfect no issues or anything. So I bought the bfgoodrich and right after I felt the car a bit sluggish. Another problem is that my car doesn’t switch to 8 gear, it’ll switch to 7th gear and then down to 6th gear and so on. One other thing I didn’t mention is that I recently also bought a replica mopar steel bumper so it added like 100 pounds. I don’t know how that would affect the car since it’s supposed to be able to tow. Anyone know why my car might be having this problem but others aren’t?

Sponsored

 

[JeezAJeep]

Love to hear the responses...seems like a smooth transition, but suprised its sluggish...beautiful Willy,s btw

 

[roaniecowpony]

Larger diameter tires take more power to turn, regardless of whether they are lighter or heavier. A larger diameter is the same as putting a cheater bar on a wrench, a little bit goes a long way in applying force of a wrench or resisting the force of the engine working to rotate the tire. Probably the next most influential characteristic is the rolling resistance of a tire, which is impacted by tire construction, tread form, width, tire pressure and other things. The weight of the tire/wheel is of much less influence.

 

[Zandcwhite]

Did you address the tire size change in the computer at all? If not your speedometer is off by 3% which doesn't help matters. A .9 inch tires size change is still a change. Extra weight is extra weight, and lowers the horsepower to weight ratio. Your most effective change with such a slight change would be a tuner. Superchips tuner will let you adjust your tire size to correct your speedo and the extra horsepower should be enough that it drives like stock or better. You could regear, but that's a large expense for a small change in tire size.

 

[roaniecowpony]

I like your choice of burger joints ?

 

[Willywong]

Love to hear the responses...seems like a smooth transition, but suprised its sluggish...beautiful Willy,s btw

Thank you, I was really surprised too because I read a lot of other people say that there was no difference in their performance.

 

[Willywong]

Did you address the tire size change in the computer at all? If not your speedometer is off by 3% which doesn't help matters. A .9 inch tires size change is still a change. Extra weight is extra weight, and lowers the horsepower to weight ratio. Your most effective change with such a slight change would be a tuner. Superchips tuner will let you adjust your tire size to correct your speedo and the extra horsepower should be enough that it drives like stock or better. You could regear, but that's a large expense for a small change in tire size.

That’s the first time I hear about that can you elaborate more. First time Jeep owner and after years of hard work I finally own mine so I’m learning a lot of new things. Would that mean I just put the new tire size on the superchips tuner and it will address the issue? I was reading about regearing too and sounded like a more expensive thing to do. Would the super chip tuner also fix the gear changing issue?

 

[Willywong]

I like your choice of burger joints ?

I knew someone would point that out ?

 

[@DesertRubi]

That’s the first time I hear about that can you elaborate more. First time Jeep owner and after years of hard work I finally own mine so I’m learning a lot of new things. Would that mean I just put the new tire size on the superchips tuner and it will address the issue? I was reading about regearing too and sounded like a more expensive thing to do. Would the super chip tuner also fix the gear changing issue?

Yeah, you'll probably want to buy a Tazer or Superchips product to adjust the tire size settings. Not telling the computer that you have larger diameter tires is likely to cause several of the issues you are reporting.

Yesterday I put 285/75/17 Falken Wildpeaks on my 2021 Willys with stock wheels and a 1.75" wheel spacer. And I ordered a Superchips product today so that the tire size can be recalibrated. However even with my larger tires than yours, I am still able to get into 8th gear no problem even before the computer adjustment. I have the 2.0T.

 

[Zandcwhite]

That’s the first time I hear about that can you elaborate more. First time Jeep owner and after years of hard work I finally own mine so I’m learning a lot of new things. Would that mean I just put the new tire size on the superchips tuner and it will address the issue? I was reading about regearing too and sounded like a more expensive thing to do. Would the super chip tuner also fix the gear changing issue?

Just correcting tire size helps, there are many ways to do this. The tazer from zautomotive, the procal snap from aev, etc. If you go with a full tune you'll need to swap out the ecu (included with purchase from superchips) but I'm a big fan of the traildash 3 on our Rubicon. Not sure which engine you have, but I'd guess it's the v6. We have the 2.0t so it's not exactly the same. The full tune also includes a transmission tune and I much prefer the way the Jeep shifts now. The pulsar is superchips piggy back unit that still allows tire size adjustment and gives a boost in performance which will help with transmission shifting, but not to the extent of a full time. The pulsar is a plug and play setup that doesn't require the ecu swap if that is too in depth for you. No experience with one on a Jeep, but it made a heck of a difference on my ram.
https://superchips.com/shop/pulsar-2018-2020-jeep-3-6l-jl-wrangler
https://superchips.com/shop/traildash-3-for-jeep-wrangler-379
Good luck and happy jeeping.

 

[Willywong]

Just correcting tire size helps, there are many ways to do this. The tazer from zautomotive, the procal snap from aev, etc. If you go with a full tune you'll need to swap out the ecu (included with purchase from superchips) but I'm a big fan of the traildash 3 on our Rubicon. Not sure which engine you have, but I'd guess it's the v6. We have the 2.0t so it's not exactly the same. The full tune also includes a transmission tune and I much prefer the way the Jeep shifts now. The pulsar is superchips piggy back unit that still allows tire size adjustment and gives a boost in performance which will help with transmission shifting, but not to the extent of a full time. The pulsar is a plug and play setup that doesn't require the ecu swap if that is too in depth for you. No experience with one on a Jeep, but it made a heck of a difference on my ram.
https://superchips.com/shop/pulsar-2018-2020-jeep-3-6l-jl-wrangler
https://superchips.com/shop/traildash-3-for-jeep-wrangler-379
Good luck and happy jeeping.

So you think the superchips won’t be as good? Or the effects of it don’t last long? I was kinda thinking about the superchips.

 

[Zandcwhite]

So you think the superchips won’t be as good? Or the effects of it don’t last long? I was kinda thinking about the superchips.

The pulsar isn't quite as good as the td3, both from superchips. If it were me I'd go td3 as that is what we run in our 2019.

 

[4x4snowmachinejeep]

Did you address the tire size change in the computer at all? If not your speedometer is off by 3% which doesn't help matters. A .9 inch tires size change is still a change. Extra weight is extra weight, and lowers the horsepower to weight ratio. Your most effective change with such a slight change would be a tuner. Superchips tuner will let you adjust your tire size to correct your speedo and the extra horsepower should be enough that it drives like stock or better. You could regear, but that's a large expense for a small change in tire size.

Do you know if this gear shifting etc. factor be the same with the diesel powertrain?

 

[gsbrockman]

I noticed hardly any difference at all going from LT255/75R17 Destination MT2’s to the LT285/70R17 KO2’s.

 

[txj2go]

There is a lot of discussion about tires and gearing and 8th gear. A lot of people do report trouble with 8th gear running larger tires.
I have a 2018 JLU Sport V6 8-speed. I put on Rubicon takeoff tires, they fit ok, no problems with the fit or the ride, but there were a lot of situations where I couldn't maintain 8th gear anymore. On the freeway at the speed limit, level ground, I could normally maintain 8th gear but any little incline or headwind and it would drop to 7th gear. I didn't really notice any changes to acceleration, it still seems to drive the same as it did before.
It is what it is, running that tire size was/is important to me for what I use the Jeep for so I have to put up with 7th gear sometimes. I also added Rubicon springs and shocks and new Mopar lower control arms. It's a little taller but it still pretty much rides the same way.

Sponsored