Who wants CTIS?
- Thread starter Metcalf
- Start date
Martinjmpr
Wiffleball Batter
My only direct experience with CTIS was on the M35A3 military trucks. This was the retro-fit of the old M35A2 deuce-and-a-half that the National Guard did about 12 - 15 years ago. They put in a new, turbocharged diesel engine to replace the non-turbo diesel, replaced the 5 speed manual transmission with an automatic, added power steering (best addition right there!) and included a CTIS. They also swapped out the 10 wheel/tire combination with skinny tires for 6 larger, "high flotation" tires.
And from what I saw, they were nothing but trouble. Maintenance nightmares.
I would imagine any decent CTIS would cost upwards of $5k to fit to an existing vehicle and would likely be nearly as trouble-prone as the M35A3.
Bottom line: Not worth it to me.
And from what I saw, they were nothing but trouble. Maintenance nightmares.
I would imagine any decent CTIS would cost upwards of $5k to fit to an existing vehicle and would likely be nearly as trouble-prone as the M35A3.
Bottom line: Not worth it to me.
dzzz
™
On some speciality vehicles adjusting tire pressure is more than an onroad/offroad decision. It's useful to adjust pressure for ride comfort in varying conditions. Plus its meant to be a safety feature on heavy vehicles with only four tires.
With big tires like Michelin XZL CTIS has become part of the design.
Would I add CTIS to a jeep? no
With big tires like Michelin XZL CTIS has become part of the design.
Would I add CTIS to a jeep? no
I did a lot of research before I went with Mog axles because I wanted CTIS. It is common on Mogs and Hummer H1's so I stuck to parts for those two vehicles. Replacement parts are common and not too expensive. I eliminated all of the electronic controls that the Hummer uses and just went with a manual pressure regulator and gauge mounted under the drivers seat for easy adjustment as I drive.
I have no idea how CTIS would be adapted to a non-portal axle design-- That would be a lot of modification and I could see reliability issues with that. But with a portal hub, it is a super simple design and not much to go wrong.
My rig was designed as a daily driver and I need to be able to drop it down to get into a standard garage. I can drop the body down by dumping the air in the airbag suspension (generally all that is required) and then if I need to go lower, I can just lower the tire pressure... I can get it into a 6' tall garage if I need to this way-- standard doors are 7' tall.
But I also like the option of airing up between trails-- like between Imogene and Engineer and Engineer and Black Bear and getting out and making adjustments takes more time than you would think--so I used to just run between trails aired down which seriously limited road speed-- and in Colorado, that really ticks drivers off.
baca327
Adventurer
Dont be discouraged Metcalf. All our military vehicles have it except the Humvee(which does not have CTIS and is also phased out and not used in combat anymore). It is a very reliable system made by Spicer Dana. Its super nice for going from highway to cross country or getting stuck. Also an option for a tire with a hole that constantly refills the tire every few seconds. Its getting better not the same as the old H1 stuff. Obviously AM General didn't find that system reliable enough to install on military vehicles.
chetcline
I was fascinated by the many comments re Central Tire Inflation. I know a lot about CTI, as I've been making and using it for nearly 15 years on a wide variety of vehicles. But first, if you don't like tools, or are too lazy to use it, or you dont care about your own vehicle, and the environment, you won't like it.
But, if you do care, then CTI is superb. Let me be a little more negative. Several comments re Cross Fire and Cat's Eyes said things like, the hoses aged after 4 or 5 years. Don't you guys change your oil, or your v belts? The hoses are parts that have a usable life, just like tires. Why blame the tool just because you don't maintain it.
Now, after my grumbles. If you spend your life on the good roads, then you won't need CTI unless you drive a truck that changes it's load and earns a living. If your truck does carry payloads, then every time you change the load you should change your tire pressures. Otherwise, you are wasting tires. Michelin states that a 20% under inflated tire wears out 20% faster, AND a 20% over inflated tire wears out 22% faster. And almost everyone runs way too much tire pressure on bigger trucks. CTI will save at least 30% of over all tire costs. These are facts that I can back up with many scientific tests, and years of personal experience.
If you get off the beaten track, you should lower tire pressures. On gravel roads, I use about 60% of the correct highway pressures. As the terrain gets worse, my pressures drop more. On my JK unlimited, I run 34 psi on the highway. If it rains, I increase pressures to around 40. If I'm fully loaded and towing a trailer, I'll run 45 to 50 psi in the rear. On gravel roads, running in normal weights, my Jeep likes 20 to 22 psi. Hard pack dirt roads like 22. Gravel roads, 20. In fire trails, I'll drop to 10 or 12 psi. And in real tough country, or sand, or mud, or snow, I'll go down to 7. Tires are stock 17 inchers.
My Suzuki Vitara with 30 inch mud terrains, I run 20 on the highway, 10 to 12 on gravel roads, and down to 4 psi in tough going.
My Chev C65 runs 445 super singles. I run 40 psi on the front and 22 psi in the rear when empty.
I had a ford Louisville tandem drive truck with a flat top. Even with the Suburban on the back, I only ran 20 psi. naturally, fully laden, I'd run up to 85 psi, which is all any legal loaded truck needs.
If you are serious about learning more, look up www.aircti.com or email me at www.chetcline@hotmail.com
Cheers
I was fascinated by the many comments re Central Tire Inflation. I know a lot about CTI, as I've been making and using it for nearly 15 years on a wide variety of vehicles. But first, if you don't like tools, or are too lazy to use it, or you dont care about your own vehicle, and the environment, you won't like it.
But, if you do care, then CTI is superb. Let me be a little more negative. Several comments re Cross Fire and Cat's Eyes said things like, the hoses aged after 4 or 5 years. Don't you guys change your oil, or your v belts? The hoses are parts that have a usable life, just like tires. Why blame the tool just because you don't maintain it.
Now, after my grumbles. If you spend your life on the good roads, then you won't need CTI unless you drive a truck that changes it's load and earns a living. If your truck does carry payloads, then every time you change the load you should change your tire pressures. Otherwise, you are wasting tires. Michelin states that a 20% under inflated tire wears out 20% faster, AND a 20% over inflated tire wears out 22% faster. And almost everyone runs way too much tire pressure on bigger trucks. CTI will save at least 30% of over all tire costs. These are facts that I can back up with many scientific tests, and years of personal experience.
If you get off the beaten track, you should lower tire pressures. On gravel roads, I use about 60% of the correct highway pressures. As the terrain gets worse, my pressures drop more. On my JK unlimited, I run 34 psi on the highway. If it rains, I increase pressures to around 40. If I'm fully loaded and towing a trailer, I'll run 45 to 50 psi in the rear. On gravel roads, running in normal weights, my Jeep likes 20 to 22 psi. Hard pack dirt roads like 22. Gravel roads, 20. In fire trails, I'll drop to 10 or 12 psi. And in real tough country, or sand, or mud, or snow, I'll go down to 7. Tires are stock 17 inchers.
My Suzuki Vitara with 30 inch mud terrains, I run 20 on the highway, 10 to 12 on gravel roads, and down to 4 psi in tough going.
My Chev C65 runs 445 super singles. I run 40 psi on the front and 22 psi in the rear when empty.
I had a ford Louisville tandem drive truck with a flat top. Even with the Suburban on the back, I only ran 20 psi. naturally, fully laden, I'd run up to 85 psi, which is all any legal loaded truck needs.
If you are serious about learning more, look up www.aircti.com or email me at www.chetcline@hotmail.com
Cheers
Here is my system: http://comancheclub.com/topic/35156-too-high-to-get-it-right-portal-comanche/page-5#entry420754
But it is on Volvo Portals... would love to see pictures of a non portal system
But it is on Volvo Portals... would love to see pictures of a non portal system
1stDeuce
Explorer
I've been thinking about CTI for quite some time, but not necessarily for wheeling. To me, the biggest opportunity for it is 3/4 and 1-ton trucks here in the US. I see several reasons why our newer trucks should have CTI, and only on the rear...
First, if you look at the door sticker on any of them, you'll see that front pressure is normally 50-60psi. Rear is almost always 80. That's to accommodate the max payload, which is almost 100% located over the rear axle. But consider that these trucks have payloads ranging from 2500 to 4000lbs, while most of the miles they accumulate are with far less than even 500lbs in the bed or on the hitch.
At 80psi, you can burn a set of tires off the back of a newer truck in 20k miles if you're running empty most of the time. This is because the contact patch on a stock size tire at 80psi under a HD truck is about 1" long. No wonder you're burning the tread off given how much power these truck can lay down, and that it's all flowing through 1" of tread across the width of the tire! Another concern is that with hard tires on a lightly loaded truck, traction is poor at best on soft surfaces. This leads to wheel hop, road washboarding, stuck situations, and torn up job sites. Take that same truck and air the rear tires down to the front pressure (or a little less as there's normally less weight on the rear axle of an empty truck), and traction goes way up on soft surfaces. By the time you're down to 35psi, there's no more wheelhop, even in sand, and you'll feel like you're in 4wd! Running reduced pressure on gravel roads also has been shown to prevent, and in some cases "heal" the washboard surface as well, and at least here in CO there's a LOT of washboarded road thanks in part I'm sure to all the HD trucks running 80psi empty.
Oh, and do I need to talk about the ride quality improvement that would come with smartly selecting tire pressure??
A modern truck KNOWS how much it weighs by the time you've covered just a mile. Use that info to force an air up for loaded trucks if the operator isn't smart enough, but at least a CTI system would let us air down the rear axle to help out all the things above!! Doesn't seem like it would require too much hardware to run CTI on the full floating rear axles of these trucks...
I think it's way past time that the OE's took advantage of all the electronics in the truck to do a rear-axle CTI system for the HD trucks. I think a lot of customers would really appreciate it. I know I would!!
So far Dodge has had the closest thing, which was a switch for "Light Load" that allowed the rear tire pressure monitors to look for 50psi or so instead of 80. That way, you could air down for an empty truck, and not be looking at the tire pressure monitor light. I believe it auto cancelled if you put the truck in tow/haul. That switch is gone now, I'm sure because of litigation concerns.
On my Jeep, I'm happy to air down at the start of a trip, and up at the end. If I'm running huge miles between trails, I may air up some to cover the distance, but airing up/down/up/down several times a day just to cover a few miles isn't something I worry about. I normally only air down to 15psi or so for most of the trails I run, and even a longer hop on pavement at 15psi isn't going to cause problems. I would get a better return out of connecting the sway bar than airing up the tires. (I usually don't do that either...)
Chris
First, if you look at the door sticker on any of them, you'll see that front pressure is normally 50-60psi. Rear is almost always 80. That's to accommodate the max payload, which is almost 100% located over the rear axle. But consider that these trucks have payloads ranging from 2500 to 4000lbs, while most of the miles they accumulate are with far less than even 500lbs in the bed or on the hitch.
At 80psi, you can burn a set of tires off the back of a newer truck in 20k miles if you're running empty most of the time. This is because the contact patch on a stock size tire at 80psi under a HD truck is about 1" long. No wonder you're burning the tread off given how much power these truck can lay down, and that it's all flowing through 1" of tread across the width of the tire! Another concern is that with hard tires on a lightly loaded truck, traction is poor at best on soft surfaces. This leads to wheel hop, road washboarding, stuck situations, and torn up job sites. Take that same truck and air the rear tires down to the front pressure (or a little less as there's normally less weight on the rear axle of an empty truck), and traction goes way up on soft surfaces. By the time you're down to 35psi, there's no more wheelhop, even in sand, and you'll feel like you're in 4wd! Running reduced pressure on gravel roads also has been shown to prevent, and in some cases "heal" the washboard surface as well, and at least here in CO there's a LOT of washboarded road thanks in part I'm sure to all the HD trucks running 80psi empty.
Oh, and do I need to talk about the ride quality improvement that would come with smartly selecting tire pressure??
A modern truck KNOWS how much it weighs by the time you've covered just a mile. Use that info to force an air up for loaded trucks if the operator isn't smart enough, but at least a CTI system would let us air down the rear axle to help out all the things above!! Doesn't seem like it would require too much hardware to run CTI on the full floating rear axles of these trucks...
I think it's way past time that the OE's took advantage of all the electronics in the truck to do a rear-axle CTI system for the HD trucks. I think a lot of customers would really appreciate it. I know I would!!
So far Dodge has had the closest thing, which was a switch for "Light Load" that allowed the rear tire pressure monitors to look for 50psi or so instead of 80. That way, you could air down for an empty truck, and not be looking at the tire pressure monitor light. I believe it auto cancelled if you put the truck in tow/haul. That switch is gone now, I'm sure because of litigation concerns.
On my Jeep, I'm happy to air down at the start of a trip, and up at the end. If I'm running huge miles between trails, I may air up some to cover the distance, but airing up/down/up/down several times a day just to cover a few miles isn't something I worry about. I normally only air down to 15psi or so for most of the trails I run, and even a longer hop on pavement at 15psi isn't going to cause problems. I would get a better return out of connecting the sway bar than airing up the tires. (I usually don't do that either...)
Chris
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