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Discussion Starter · #1 ·
1. Extended use at elevated RPM levels, be it enhine holdback, or towing up a long mountain pass, or 4wheeling, how hard is it on the engine to run at say 4,000-5,000 RPM levels for maybe 5 to 10 minutes at a time.

2. Backing in to launch my boat or Seadoo, should I leave it run when in the water or shut it off? Also how far can I safely back in without water damaging the engine, interior, electrical, rear differential, or other parts? Sometimes it may need to sit for a few minute on the launch ramp. Is water up to the bumper a safe level still, or too deep. My boat trailer is tall, and the ramp I use most at a shallow angle, requiring I back in a fair ways to launch and retrieve my boat is why I ask.

3. Is there an ideal tire pressure to use in the stock tires on a Rubicon?

4. What is an expected range per tank of gas, yes it will depend on driving I do realize. But should it still go 200 miles about 300 kilometers per tank on trails? And how accurate is the Petrol gauge in the new generation Jeeps. I ask because my current car and truck show empty, but when filled up, take much less than the manual says their capacity is. Leading me to believe the gauge is wildly inaccurate, and not to be trusted. Is the Jeeps the same way, it may say empty, but you have much petrol left in the tank.
 

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1- not sure but if it's outa the redline it should be ok

2- leave it running, it'll keep water from where it's not supposed to be

3- it should say what the tire pressure on the sidewall of the tire, I'd follow that for road driving

4-I'm not sure on the JK but when my tj was on 35's it'd go about 213ish miles before I'd get real nervous
 

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1. Extended use at elevated RPM levels, be it enhine holdback, or towing up a long mountain pass, or 4wheeling, how hard is it on the engine to run at say 4,000-5,000 RPM levels for maybe 5 to 10 minutes at a time.

No it won'at hurt it at all, unless the engine temp goes up more than 20% or so. Do not exceed red line as mentioned. It is going to suck a lot more gas at the higher rpms.

2. Backing in to launch my boat or Seadoo, should I leave it run when in the water or shut it off? Also how far can I safely back in without water damaging the engine, interior, electrical, rear differential, or other parts? Sometimes it may need to sit for a few minute on the launch ramp. Is water up to the bumper a safe level still, or too deep. My boat trailer is tall, and the ramp I use most at a shallow angle, requiring I back in a fair ways to launch and retrieve my boat is why I ask.

Launching: First unplug the trailer wiring before backing into the water in case the trailer tail lights have a leak. If you have a good seal around your doors you can submerge the Jeep pretty deep actually. Keep the engine running. It eliminates water from running into your exhaust and getting in your muffler or cat. The top of the back tire is pretty much the deepest you want to go as a rule. Use good judgement.

3. Is there an ideal tire pressure to use in the stock tires on a Rubicon?

As mentioned, it will say on the side of the tire. A lot depends on the type of tire.

4. What is an expected range per tank of gas, yes it will depend on driving I do realize. But should it still go 200 miles about 300 kilometers per tank on trails? And how accurate is the Petrol gauge in the new generation Jeeps. I ask because my current car and truck show empty, but when filled up, take much less than the manual says their capacity is. Leading me to believe the gauge is wildly inaccurate, and not to be trusted. Is the Jeeps the same way, it may say empty, but you have much petrol left in the tank.
Range obviously will vary with conditions and the driver. As far as off road, you will consume much less gas because you are driving much slower. I can wheel all day on a quarter tank. Once I'm on the road the gas goes quickly. The type of terrain makes a difference too. If you have a heavy right foot off road, which is not the way the vehicle is designed, you will consume more gas. Easy on the skinny pedal. Let the gears do the work.
 

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Discussion Starter · #5 ·
I always unplug the trai'er first, but thanks for pointing that out, as some do not know to.

There should be no need to go as deep as the top of the rear tire ever. So should be good there.

Stock I believe it will come with B.F.Goodrich Mud Terrain tires. But the sidewal pressure listing according to what I can find is a maximum, not the operational pressure. I just hoped for a good operational pressure idea for an all around useage.
 

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The owner manual doesn't cover tire pressures?
 

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I always unplug the trai'er first, but thanks for pointing that out, as some do not know to.

There should be no need to go as deep as the top of the rear tire ever. So should be good there.

Stock I believe it will come with B.F.Goodrich Mud Terrain tires. But the sidewal pressure listing according to what I can find is a maximum, not the operational pressure. I just hoped for a good operational pressure idea for an all around useage.
You should have a sticker on the driver's side door frame with the recommended tire pressure for road use. Of course, if you push it to near the maximum rated when cold, you would get better gas mileage (assuming normal driving habits and not lead-foot driving) though you'll get different wear on the tires. I get 22-25 mpg with my JK at about 34psi and holding just over 60mph. If I slowed to 55mph I could probably do even better.
 

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You should have a sticker on the driver's side door frame with the recommended tire pressure for road use. Of course, if you push it to near the maximum rated when cold, you would get better gas mileage (assuming normal driving habits and not lead-foot driving) though you'll get different wear on the tires. I get 22-25 mpg with my JK at about 34psi and holding just over 60mph. If I slowed to 55mph I could probably do even better.
Sidewall tire pressure was one of the big problems with the Explorer/Firestone fiasco. Go by what the VEHICLE manufacturer recommends.
 

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Sidewall tire pressure was one of the big problems with the Explorer/Firestone fiasco. Go by what the VEHICLE manufacturer recommends.
I'm not driving an Explorer, though I am using Bridgestone (Firestone) tires. On the other hand, I also don't drive like an idiot and stress the Jeep or the tires that way. I'm not that worried about tread wear and I drive the road conditions; I also get about 20% more gas mileage than rated both in city and highway driving. I could probably do even better if I held RPM down to 1500 once at road speed.
 

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I'm not driving an Explorer, though I am using Bridgestone (Firestone) tires. On the other hand, I also don't drive like an idiot and stress the Jeep or the tires that way. I'm not that worried about tread wear and I drive the road conditions; I also get about 20% more gas mileage than rated both in city and highway driving. I could probably do even better if I held RPM down to 1500 once at road speed.
The problem isn't the Explorer, it's that the tire manufacturer's recommendations didn't match. People were overinflating the tires for the vehicle's weight and handling characteristics, items taken into account in the vehicle manufacturer's recommendation, NOT on the sidewall of the tire.
 

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Discussion Starter · #12 ·
All I know is that sometimes the manufacturer guesses at a pressure, and while its okay, it might not be ideal. Sometimes a group of owners figures out something a bit better. I am not saying anyone should radically alter pressures, but let's say they find one end should have 4 psi less than the other, due to real world loading. In my car I don't run builders specs, or the same in all 4.
 

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The problem isn't the Explorer, it's that the tire manufacturer's recommendations didn't match. People were overinflating the tires for the vehicle's weight and handling characteristics, items taken into account in the vehicle manufacturer's recommendation, NOT on the sidewall of the tire.
The problem WAS the Explorer, or rather, the company's recommended tire pressures for the vehicle. As I remember, Ford changed the recommended tire pressures at least twice in their attempt to reduce the risk of rollovers and ended up suggesting even softer tire pressures than most consider safe on the highway (and destroying gas mileage while they were at it.) I'm not certain now of the exact specifics, but I believe Ford had installed altogether the wrong tire under the truck on top of which the suspension was simply too... soft, designed more for a comfortable ride than properly carrying that load. When that incident happened, the Explorer (now Expedition) rode more like a barge on the high seas. It's no wonder the beast rolled over in sudden maneuvers--it could hardly support itself under normal driving conditions. I know several people who owned Explorers of that year grouping and they hated the way it drove. I'll grant the thing isn't supposed to be a road racer, but the amount of body roll they experienced just taking a normal curve at the speed limit frightened them. They traded out as soon as they could afford to.
 

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I'm not driving an Explorer, though I am using Bridgestone (Firestone) tires. On the other hand, I also don't drive like an idiot and stress the Jeep or the tires that way. I'm not that worried about tread wear and I drive the road conditions; I also get about 20% more gas mileage than rated both in city and highway driving. I could probably do even better if I held RPM down to 1500 once at road speed.
(Yes, I'm quoting myself)

I ran an experiment after I wrote the above comment where I short-shifted at 2000 RPM and drove steady at 1500 RPM in top gear (about 45mph) and moved my mixed traffic gas mileage from roughly 16.9mpg to 18.4mpg--obviously the acceleration stages using the most gas. That's with me currently running Jeep-recommended pressures on all four tires. While I'll admit 45mph on the freeway or even some highways is unsafe, staying at or below the posted speed limits will help save gas. My '08 seems to do its best for highways at 55 - 60, though admittedly would do better between 50 -55 if freeway traffic didn't try to force you faster.
 

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The problem WAS the Explorer, or rather, the company's recommended tire pressures for the vehicle. As I remember, Ford changed the recommended tire pressures at least twice in their attempt to reduce the risk of rollovers and ended up suggesting even softer tire pressures than most consider safe on the highway (and destroying gas mileage while they were at it.) I'm not certain now of the exact specifics, but I believe Ford had installed altogether the wrong tire under the truck on top of which the suspension was simply too... soft, designed more for a comfortable ride than properly carrying that load. When that incident happened, the Explorer (now Expedition) rode more like a barge on the high seas. It's no wonder the beast rolled over in sudden maneuvers--it could hardly support itself under normal driving conditions. I know several people who owned Explorers of that year grouping and they hated the way it drove. I'll grant the thing isn't supposed to be a road racer, but the amount of body roll they experienced just taking a normal curve at the speed limit frightened them. They traded out as soon as they could afford to.
During testing the Explorer rolled more often than Ford wanted to admit, so yes they lowered the recommended tire pressure on the sticker that apparently nobody reads. Firestone kept their recommended pressure high. I agree they were the wrong tires...either Firestone needed to strengthen them or Ford needed to make another selection when they decided to air down.

However the vehicle itself wasn't really a problem in the real-world rollovers, the NHTSA didn't see any evidence that the Explorer was more prone to rollovers following tread separation than other SUVs.

With modified vehicles, absolutely pressure can change. But if you're running a stock-ish vehicle of about the factory weight, with OE-style suspension, go with the sticker, not the sidewall.
 

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Ok, I'm not disagreeing with your core statement of "follow the tire pressures listed in the door frame". This is, as you say, the best recommended pressures for the vehicle's purpose. However, on a vehicle meant to have a comfortable ride, naturally you want the suspension to absorb as much of the road impact as possible and the tires, especially high-profile tires like -75s or -80s will absorb most of the road roughness by deforming the sidewalls so the impact never even reaches the wheel itself. Softening the tires increases this smoothing effect, but also permits more vehicle roll on cornering and heats up the tire itself. Most tire blowouts are due to overheated tires due to too-low air pressure. Worse, too many drivers simply don't pay attention to their tire pressures and if you do happen to go to a gas station that still offers full service, I have seen them literally air down hot tires to rated pressures, which is the absolute worst thing they could do.

With my own mother's Cadillac whose tires were clearly well below rated pressure, I went to such a station and asked them to air the tires up. I didn't have an air pump handy and the next nearest self-serve station was another couple miles down the road. Instead, I heard him letting air out of the tires and when I asked him why he said, "They were over the sidewall pressure rating." Well duh. They were already low on pressure, carrying a heavy car on a hot summer day. Naturally they would generate more than the rated COLD pressure. The guy couldn't understand that those ratings are for cold tires at roughly 70 degrees. I had to guess how much he'd bled out (about 2 pounds each) and pump in almost 10 pounds per tire at the self-serve station just to get the tires to look right. After parking her car back in the garage overnight I checked the pressures and found them within one (1) pound of door frame ratings all around. So I might agree that up to a point the Explorer was OK, that doesn't absolve the driver or Ford themselves for other errors.

In the particular case of my JK Unlimited, I've found that adding about 2 pounds to the rated door-frame pressure does improve my gas mileage though I admit it does make the Jeep ride a little harsher on its 18" tires. (32" OD.) I accept the ride difference and have found that overall the Jeep feels better for road driving than it did at stock pressures. Naturally, if I'm going to ride an off-road park I'll air down for better traction, though without bead-lockers, I don't dare go much below 20psi or I risk spinning the wheel in the bead or even losing all the pressure if I slip on a rock or stump and knock the bead free. Of course, as Jeepers most of us are aware of this and that's exactly why bead-lock rims are available.

Simply put, being a good driver you're more likely to pay attention to your tire pressures than the average driver and as such you use the door-frame ratings as a guide, not an absolute rule. An 'average' driver needs to use that rating as a set-in-steel rule.
 

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1. Extended use at elevated RPM levels, be it enhine holdback, or towing up a long mountain pass, or 4wheeling, how hard is it on the engine to run at say 4,000-5,000 RPM levels for maybe 5 to 10 minutes at a time.
I ride my JK in that range often. Also for extended periods in very hot climate, when in 4LO and having to get enough speed to climb very high sand dunes. It sounds like a hornet. By the way, the r.p.m. are automatically limited, I can not even get into the red range.
So far I have no issues with 12,000 km on the odometer, but am sure also that the engine wear will be higher than with lower r.p.m. As others said, just watch the engine temp, this may climb up and there is no limiter.
 

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3. Is there an ideal tire pressure to use in the stock tires on a Rubicon? /QUOTE]

The label in my driver's door frame says 35 psi for both front and rear. Overinflating as well as underinflating reduces tire life. Overinflating results in more tread abrasion in the middle, underinflation in more tread abrasion on the sides. Underinflation also results in more fulling (is that the correct word ?) of the sidewalls, thus heating them up, and is much more wearing than overinflation.
In soft sand I go down to 12 psi to increase the footprint and get better floating, but I inflate to 35 immediately when I reach the road again. If with very low pressure on the road and no chance to fill, drive SLOOOOWLY !
Another tip: Fill the spare tire from time to time unless you have a compressor on board.
 

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Discussion Starter · #19 ·
I planned to just try it some myself since it does not seem many experiment much. Adding, or reducing a few psi. The weight bias is front heavy, and since many also carry a winch, and that is weight very far forward, it only stands to logic that the front tires should have more psi that the rears. It is odd they just give a psi rating the same for all 4 tires. In my daily driver car I run differing pressures front to rear as well. And my pickups usually never have the same front to rear. Unladen I run my pickup tires at 45 on the rear, loaded heavily I run 80 rear. In the front tired I run 55 always.
 

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The proper air pressure will vary through different types of tires as well. The sticker on my door frame says 33psi, but I run 28 front, 26 rear. The sticker on the door takes into account STOCK sized tires, and no mods. Kelowna, since your Jeep will be brand new, and fully stock here's an experiment for you , to see if the pressure listed on the sticker is proper for your jeep with the BFG KM2s that come on it. Set your pressure to the amount on the sticker. Then take some chaulk, and mark your tires accoss the tread (do this in several places on the tire). Then go for a drive. The marks will wear off evenly across the tread if you are at the proper psi. If you're high, it will wear iff in the middle; low , wears on the outsides. When your chaulk marks get to wear off evenly, you have a proper tread contact with the road, resulting in even tread wear, meaning you are at the best ideal tire pressure. This works for any vehicle, and all sizes/type of tire.:cool:
 
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