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I live in Colorado. My apartment is at 7,000 feet, and there are plenty of highways that are at 9,000 - 10,000 feet.

At this altitude, a naturally-aspirated engine loses about 20%-30% of it's horsepower relative to sea level. So, the Pentastar in my 2014 JKUR is producing around 210 hp.

So far, the drivetrain is stock. I have an automatic transmission and the 4.10 axle ratio, and the stock 32" Rubicon tires.

I am considering buying a lift and going to 35" tires, but worried about the effect on performance at this altitude and whether I would need to regear. Plus the weight from bumpers and a winch at some point...

I am okay with the performance now, but it is certainly not quick, and I am concerned that it will feel slow and labored with 35" tires. I see lots of people saying they don't have a problem with the performance with 35s, but they're at or near sea level - their performance with 35s is probably pretty close to what I get for stock performance.

Anyone living in the high country who can weigh in? Is a JKUR with 35s and some extra junk manageable with the stock 4.10 gearing, or is a regear necessary?
 

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I'll probably know real soon, but I am curious about that myself.

Honestly I think it's about expectations. Realistically, the 4.10 with the new engine and transmission is great for 35s, but it will feel slower than the 32"s.

I don't expect I would mind since I really drive the Jeep differently than any other car I have. That said, when I borrowed a friend's TJ with 33's and drove it over Berthoud Pass.... not fun.
 

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I have that set up. 3.5 lift with 35s with 4:10 auto. I have Cooper st Maxx tires so there is far less rolling resistance vs the Bf mud terrains I had. It is a little slower but it is seriously nothing to even think twice about. Make sure you recalibrate with a pro cal or something for the bigger tires. Before I re calibrated it seemed to search for gears a lot. After the re calibration it was back to normal. I can easily do 75 to 80 on the freeway with this set up. But I find that I drive my jeep slower so I keep it around 70. In town it's not an issue at all. I definitely have no regrets and don't plan on regearing. Since I went 3.5 with the lift I also changed out the front DS.
 

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I'm getn some 35s Friday on my 2010 2 door jk sport that has 4 inch lift on it do I need to regear and if so how much does it usually cost
 

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I was under the impression it would be over a grand to do it.
 

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I live in Colorado. My apartment is at 7,000 feet, and there are plenty of highways that are at 9,000 - 10,000 feet.

At this altitude, a naturally-aspirated engine loses about 20%-30% of it's horsepower relative to sea level. So, the Pentastar in my 2014 JKUR is producing around 210 hp.

So far, the drivetrain is stock. I have an automatic transmission and the 4.10 axle ratio, and the stock 32" Rubicon tires.

I am considering buying a lift and going to 35" tires, but worried about the effect on performance at this altitude and whether I would need to regear. Plus the weight from bumpers and a winch at some point...

I am okay with the performance now, but it is certainly not quick, and I am concerned that it will feel slow and labored with 35" tires. I see lots of people saying they don't have a problem with the performance with 35s, but they're at or near sea level - their performance with 35s is probably pretty close to what I get for stock performance.

Anyone living in the high country who can weigh in? Is a JKUR with 35s and some extra junk manageable with the stock 4.10 gearing, or is a regear necessary?
I'm pretty much in your exact scenario. I'm at the base of Tahoe at about 6800 feet above sea level. I have a 2015 Rubicon with 4:10 gears, 3 inch lift and 35 inch tires. Having driven with the stock 32's for a while prior to my lift and tires, I had a good sense of the difference before and after. Surprisingly, acceleration didn't suffer too much at all, which surprised me. Braking on the other hand, did noticeably suffer. Not horribly but I noticed right away that I had to put a bit more pressure on the brake pedal to stop. It's nowhere near dangerous or anything but noticeable. Personally, I don't have any thoughts about re-gearing because it seems perfect as is. Hope this helps.
 

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You will be fine with that set up as long as you aren't fully loaded or towing. Just remember that it is just a little v6. try to get your RPMs in the power band. But 90% of the time you will do fine. With 35s the 4.10 is going to give you a good RPM for 75 mph Colo highways, but your auto will search for a good gear a lot, but you will get used to that.
 

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Happy with 35s and 4.10s? I certainly am. I wheel my 2015 2dr Rubi in the Texas hill country and think it is a great set-up. Of coarse, I am at sea level.
However, I will find out how this set-up does at altitude this summer as I am attending the Roof of the Rockies Jeep Jamboree in Aspen.
 

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Just curious are most rubi owners with the 4.10s happy on 35s? Wheelin etc
Yes, totally.

My JKR has 35" tires and 4.10, and reacts noticeably quicker than my JKUS with 33" tires and 3.73.

Any you gotta love the 4.10 + 4:1 transfer case wheeling either up or downhill...as is the norm around here.
 

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I'm in Utah, the 4:10 s are fine. You'll notice most at freeway speeds, but not terrible. It wants to downshift to 4th a lot. Braking is where you really notice a difference. I put Dynatrac Pro Grip brakes on and the brakes feel better than stock now..
Brakes are on the list for sure. I remember going from the stock 16s to rubi takeoffs how much more I had to press on the pedal. I am mounting my 35s this week so I am expecting alot worse.
 

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Brakes are on the list for sure. I remember going from the stock 16s to rubi takeoffs how much more I had to press on the pedal. I am mounting my 35s this week so I am expecting alot worse.
That's how I felt when I put 35s on my JK put the Dynatrac kit on the JKU at the same time as the tires and the braking may have actually improved. I really recommend it.
 

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I live down in SW Colorado p, house at 7200ft with 3:73 & 285/70/17. I don't find it to be a problem. Yes it does down shift on small climbs and runs at higher RPM's, but I have what I think is enough power. I also have a small M416 type trailer (1200lbs load) and that does work the engine more but it will still hold the speed limited. If I need more power or speed, I get that in the summer with the sports car.
 

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I find the motor a bit too gutless at altitude. I have 4.10 with 35s. It is annoying when loaded down. While a regear will certainly help, the lack of torque will still be felt. I live at 6,000 feet and have a condo at around 9,000 feet. We prefer taking the 4Runner every time unless offroading. I am considering a regear but I have some other financial priorities I have been putting off so let's see how much it annoys me this year. :pullinghair:
 

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I'm just less than 4000ft but frequently drive and wheel at much higher altitudes, I was unhappy with 3.73 and 33's and ended up running 5.13 with my 35's.
The Rubi T-case will help off road and should work well, on highway it will be a bit gutless when pulling hills but if you don't mind a bit of lugging and frequent downshifts it should be perfectly tolerable
 
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