I've been running 35's with 3.73 gears on my 6 speed 4 door for the last 4 months here in Colorado. They're fine around town, but as soon as you get out on I-70, it's easy to feel the difference. Like other guys have said, you have to be shifting down into 4th before the hill starts.

Douchey tourists from texas in their mini-vans go wizzing by, giving us dirty looks because they don't understand. As long as you don't mind running at 4K+ RPMs and not passing anybody except on a downhill, its fine. Gears are in my future, but I can probably live without them until next spring.

I have a Superchips now, which helps, but its no substitute for gears. However, think back to when your jeep was stock. I don't remember ever wizzing by anybody in the fast lane on a mountain pass. This is a jeep, not a Bugatti.

 

I have a HEAVY Rubicon and just going up to 5,000 ft. my Jeep would scream in 2nd and third gear. My transmission just could not maintain the speed. Turning off the overdrive did not seem to help. I see you have an Automatic, so you may want to rear to 538 due to your tire size. I have 513 because I will not go larger than 33". Going downhill, you will be braking a lot, but your gas mileage will get better (ha ha ha). Plan not to be in a hurry and watch your RPM and Trans Temp going up hill.

 

Some of you low elevation guys are just spoiled. I have driven over the "pass" I-70 from Denver to Junction probably 150 times, and you just get so used to it you don't think about it. Had my Wrangler up to 14k feet and thought it did fine. But went out west to the coast, and DAMN - felt like a totally different vehicle.

It isn't bad to answer the original question. With 35s, you are probably going to have to go slower - but on the passes out here, that isn't at all unusual. It is hard on cars, and there are plenty of lanes for the slow cars. Just enjoy the trip - its beautiful.

 

6-speed, 4.10's, and 34" MTR/K tires.

I drove up I70 from Frisco to the Eisenhower Tunnel today, and due to being on the phone I had the A/C on and the windows up. I'm not one to rev the crap out of my engine, so I prefer to keep it between 3000-3500 rpm and just get in the slow lane. I was down to 3rd, being passed by every single vehicle on the road except for the trucks.

The "performance" of the 3.8 is laughable, so thats exactly what I do; laugh. Its fine for most roads though, and when wheeling at high altitudes I've never had a problem. But on the highway, just look for me struggling to hold 40mph and give a wave, cause I'm not going anywhere fast for quite a while.

 

I have 33's and an auto with 3:73's. I live above 6000 feet and drive up and down the mountain 4 days a week. I never even come close to hitting 5000 rpm. usually between 2800 and 3700 rpm. Usually in 3rd gear and when I hit a steeper grade, 2nd gear at about 3000 rpm. I don't usually get passed by other cars. I zip up the mountain ok. Of course I want to regear as soon as I can, but for now, it's really not a big thing. I just know how to drive the mountain I guess.

 

Well said drgreybow, we don't drive Vetts, we drive Jeeps, all this whining drives me crazy, I drove the I-70 2 years ago no problems, I pulled a trailer (2000lbs) from Calgary to Vancouver and back at higher elevations than Colorado Rockies with no problems. I'm obviously doing some down shifting but I really don't get everyones complaint about being under powered in the mountains. The TJ 4.0 was way worse IMO. Maybe it's my CAI and exhaust, don't know, but I can tell you that I bought a Jeep and am breaking no land speed records, like drgreybow said enjoy the montains they are breath taking and if it takes you a couple extra hours, so what!!!

2008 Unlimited Rubicon with 35"s