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Discussion Starter #1
Hi guys,

I picked up a 2016 JKU Sport a couple weeks ago. The vehicle is stock, including the stock 16" steel wheels with 225/75R16 tires. They look lost under the fender flares, so I ordered a set of 17x9 Mammoth Boulder wheels with 265/70R17 BF Goodrich K02's from Extreme Terrain.

My reason for going with the 265/70R17 tires was that it's running with the stock 3:21 gears. By my calculations this tire size equates to 31.6 inches by 10.43 inches wide. From your experience, what tire size can I go to without unduly affecting performance? The Jeep is an auto, and I use it mainly for road and light offroad. In the future I may go to 33's and call it a day, so I want to be prepared.

Thanks
Colin
 

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Naw, you're fine with the slightly larger tires. I think the 32's were an option with the same gearing as what you have. You'll want to either have the dealer adjust for tire size in the PCM, or get yourself a programmer and DIY.

If the 3.21 gearing is too sluggish for you, I'd recommend finding a set of used rubi axles (4.10 gears) and armor them up a bit. Have fun!
 

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Hi guys,

I picked up a 2016 JKU Sport a couple weeks ago. The vehicle is stock, including the stock 16" steel wheels with 225/75R16 tires. They look lost under the fender flares, so I ordered a set of 17x9 Mammoth Boulder wheels with 265/70R17 BF Goodrich K02's from Extreme Terrain.

My reason for going with the 265/70R17 tires was that it's running with the stock 3:21 gears. By my calculations this tire size equates to 31.6 inches by 10.43 inches wide. From your experience, what tire size can I go to without unduly affecting performance? The Jeep is an auto, and I use it mainly for road and light offroad. In the future I may go to 33's and call it a day, so I want to be prepared.

Thanks
Colin

It really depends on the terrain, flat vs hilly, how fast you will be going, what you using it for, ect.. If you are driving it on fairly flat terrain you will have no problems, possible slight difference in pep going up hills, people put on 35’s with 3.21 gears which is doable but would assume sluggish. I have 265/70/16 Coopers and upgraded to 4.88 gears, where I live you are either driving extreme uphill or downhill ave 20-35mph, I might hit 40mph 1x per year. If I lived in Florida I would not regear. My Coopers measured under load are actually 30inch even thought they state 31.6
 

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Discussion Starter #4
Hi guys,

I picked up a 2016 JKU Sport a couple weeks ago. The vehicle is stock, including the stock 16" steel wheels with 225/75R16 tires. They look lost under the fender flares, so I ordered a set of 17x9 Mammoth Boulder wheels with 265/70R17 BF Goodrich K02's from Extreme Terrain.

My reason for going with the 265/70R17 tires was that it's running with the stock 3:21 gears. By my calculations this tire size equates to 31.6 inches by 10.43 inches wide. From your experience, what tire size can I go to without unduly affecting performance? The Jeep is an auto, and I use it mainly for road and light offroad. In the future I may go to 33's and call it a day, so I want to be prepared.

Thanks
Colin

It really depends on the terrain, flat vs hilly, how fast you will be going, what you using it for, ect.. If you are driving it on fairly flat terrain you will have no problems, possible slight difference in pep going up hills, people put on 35’s with 3.21 gears which is doable but would assume sluggish. I have 265/70/16 Coopers and upgraded to 4.88 gears, where I live you are either driving extreme uphill or downhill ave 20-35mph, I might hit 40mph 1x per year. If I lived in Florida I would not regear. My Coopers measured under load are actually 30inch even thought they state 31.6
Thanks for your input. Now that I have the wheels and tires on, the only thing I notice is it holds on to 3rd (auto box) going uphill, whereas before it didn't. Other than that, no difference. Those BFG K02's are awesome. Quiet on the road. Gas mileage is about the same.

Colin
 

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I think you should still look into getting the programmer. I use the AEV Procal - you can get them anywhere online and they are cheap enough when you consider what they do. You can recalibrate your speedo for your new tires - now and later on when you decide to upgrade to 33s. You can also use it when you air down while offroading to pickup more traction. You use it to set the warning to a new pressure to match your aired down setting or just turn off the warning completely like I do. Then turn it back on when you return to pavement and air back up.

It also reprograms things like turn signals and daytime running lights and other stuff. Check into it. You won't be disappointed.

Also, on the regearing thing. Don't do it. It isn't necessary. I'm running 4.88s with 37s and with 40s. But the key here is I do it to regain low-end grunt. I am perfectly fine with losing top-end and I'm okay with losing gas mileage. It doesn't sound like that's a trade you're willing to make. It isn't necessary for you, so I'd hold tight with the 3.21s you're running.
 

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Discussion Starter #6
I think you should still look into getting the programmer. I use the AEV Procal - you can get them anywhere online and they are cheap enough when you consider what they do. You can recalibrate your speedo for your new tires - now and later on when you decide to upgrade to 33s. You can also use it when you air down while offroading to pickup more traction. You use it to set the warning to a new pressure to match your aired down setting or just turn off the warning completely like I do. Then turn it back on when you return to pavement and air back up.

It also reprograms things like turn signals and daytime running lights and other stuff. Check into it. You won't be disappointed.

Also, on the regearing thing. Don't do it. It isn't necessary. I'm running 4.88s with 37s and with 40s. But the key here is I do it to regain low-end grunt. I am perfectly fine with losing top-end and I'm okay with losing gas mileage. It doesn't sound like that's a trade you're willing to make. It isn't necessary for you, so I'd hold tight with the 3.21s you're running.
Thanks. I picked up the Superchips programmer and recalibrated the speedo. I also scanned for codes because my ABS and traction control lights were on. Turned out it was a rear wheel ABS sensor, so I've ordered two and I'll replace the failed one and keep the other one, as it seems this is a common problem. That, and the battery suddenly died last weekend. Jeep only has 19000 miles but is 3 years old. The battery was the original Chrysler one.

Thanks for all your advice, guys.

Colin
 

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That's awsome. Yeah, I've had a few of those ABS sensors go bad. I think they put them on there as a way to have constant income flowing in for Chrysler - or Fiat and Chrysler now since 2009. That programmer has already paid for itself! Great Job!
 
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