The custom auxiliary fuel tank project for our 2017 Ram/Cummins 2500 is underway! June 2019 I added two additional aluminum toolboxes aft-axle on my Hallmark Nevada Hillsboro flatbed camper outfit. My idea was to eventually remove one of the large, 30-inch-long front boxes and replace it with a fuel tank, preferably a commercially available aluminum saddle tank for a medium-duty truck.
The tank project was moved to the back burner and a year passed quickly. For a while I considered a much smaller 10 or 12-gallon tank, hoping to fit one under the chassis between the frame rails, and in front of the spare tire. Just 100 miles of additional range would be a game changer during long highway trips.
Evan a commercially available tank would have required custom mounts and modifications, and surely some compromises. After discussing the project with Chris at High Sierra Fabrication several weeks ago, we decided on a custom tank for my original under-bed location. The goal was to fabricate a tank that looks extremely similar to the toolbox that was removed, and the matching 30-inch box still on the passenger-side.
Custom costs more, takes time, and is never snag-free, but if you have the right business and people involved, the results can be fantastic.
A beautiful tank was constructed using 3/16-inch diamond plate aluminum. Then High Sierra Fabrication proceeded to drill and cut holes in the box, weld-in fittings, a sump, and clean-out port, etc. We are getting close, but still working on it.
After High Sierra Fabrication completes most of installation, I will still need to plumb and wire the external pump to transfer the auxiliary fuel into the 2017 Ram’s factory tank.
Cooper STT PRO 295/65R20 (35.4″), ready to winch under a 2017, fourth generation Ram/Cummins 2500.
Question: How much spare tire can you fit under your truck?
Answer: It depends.
This post is about squeezing a large (35.4-inches) tire into the stock location on a late-model, fourth-generation, Dodge Ram Cummins pickup.
Both my Ram 2500 trucks (2014 and 2017) have had the tailpipe heat shield removed to facilitate winching a much larger tire into the factory spot. Obviously a bigger tire sits closer to the tailpipe. Only you can decide if it’s too close for you and your application. This Cooper Tires STT PRO is only about one-inch from the tailpipe; close!
35.4″ Cooper STT PRO spare is close the factory tailpipe on this 2017 Ram/Cummins.
For several years I have carried oversized rubber in the factory location on my fourth-generation Ram/Cummins trucks, mostly tires that were 34.8-inches tall. The 295/65R20 Cooper Discoverer STT PRO is substantially taller.
This 2017 Ram has plenty of clearance for the rear-axle track bar.
My 2017 has less room overall than my 2014, as the factory trailer hitch receiver is still in place. (It was removed on the 2014.) There are also steel plates on the inside of the frame to mount the Hillsboro 2000-Series aluminum flatbed. The 3/8-inch plates, one on each side, consume 0.75-inches.
3/8-inch steel plates inside the frame are part of the flatbed mounting.
There are advantages to choosing 35-inch or smaller tires on late-model, heavy-duty trucks instead of the popular 37-inch versions, particularly if they will fit in the factory spare location. These include, but are not limited to, not needing an additional tire carrier or pushing a truck camper further aft to fit a spare in front of the camper (which increases rear-overhang, tail-swing, and impacts weight distribution). Unless your rig is geared low—and most new vehicles have tall gearing—the taller overall gearing that results from fitting larger diameter tires is often a negative, as it results in less torque at the wheels.
Many should ask themselves if they really need the extra clearance provided by 37-inch rubber, or are they just following the crowd, and potentially making unnecessary compromises. There are positives and negatives for nearly every modification and upgrade choice. Generally we need to give something to get something. Everyone should decide for themselves if the juice is worth the squeeze.
35.4″ Cooper STT PRO stuffed under a 2017 Ram/Cummins 2500.
Attempted to establish a baseline for fuel economy/mpg at 65 mph, with the 35.4″-tall, 295/65R20 Cooper STT PRO tires under a heavy Hallmark flatbed truck camper outfit. There was too much wind for this to be a true baseline, but efficiency was still good for this not-aerodynamic configuration; just under 13 mpg. I probably will revisit this in the future.
20-inch vs. 18-inch Cooper Discoverer AT3 XLT heavy-duty application tire evaluation.
Tires As Suspension
In the high-performance car (and even sport-truck) world it’s obvious that tires are a critical part of the suspension setup and the overall dynamics and handling of a vehicle. In the heavy-duty pickup world tires should be regarded with similar importance regarding how they handle loads, although it seems this is frequently ignored or overlooked until a problem arises. Such laissez-faire attitude seems more prevalent with those who infrequently work their trucks.
Unless one is never going to load their rig, generally aftermarket tire-and-wheel combinations should not have less capacity than the originals. However, just because a tire can support a particular load does not mean it is providing optimal performance. There are many potential differences, which include the tire size, load index, maximum psi, construction, tread pattern and compound, etc. Here is a real-world example of how dramatically tires can affect handling?
Surefooted Mule To Wallowing Pig
While driving to the 2019 Overland Expo West show last May, my ‘Mule started handling poorly. What I discovered, arriving in Flagstaff, Arizona, was that I had lost a bolt clamping the anti-roll bar to the rear axle. This rendered the bar useless and explained the sketchy handling I was experiencing.
On a coil-sprung vehicle, particularly one with a maximum and tall load, body-roll bars can be critical for safe handling, particularly during emergency maneuvers. To mitigate the then unexplained sloppy handling, twice I stopped to increase tire pressures. Adding 20 psi and over-inflating the 65-psi-maximum tires made a slight but still noticeable stability improvement. It firmed-up the relatively tall and flexible 35” tire sidewalls on 17” wheels, partially compensating for the looseness of the disconnected rear body-roll bar.
Missing bolt and bent Hellwig Big Wig rear stabilizer bracket explained the loose handling.
Thankfully my friends at Factor 55 had a block of titanium on which we pounded the deformed bushing bracket back into a usable shape. Another friend had a spare fastener. Seems losing anti-sway bar bolts on late-model Ram 2500s is not that uncommon. My friend was carrying a spare bolt because he had previously lost one himself; we both have the same Hellwig Big Wig rear bar. Another acquaintance at the event had also found a bolt missing on his factory rear bar while in Death Valley. So owners of newer Rams might want to check their sway-bar hardware, add some Loctite, and torque ‘em.
Air Supports Weight
It’s important to remember that it’s the total amount of air in a tire that supports weight; this includes the physical volume combined with the psi. This is one reason why some of the super-short sidewall tires are not appropriate for heavy-duty pickups; the ratings can be ridiculously low, partially because there is not enough physical space for adequate compressed air.
Unreasonably short sidewalls (think low-rider) will provide a firm, sometimes even jarring ride over small imperfections in the roadway, and in extreme cases potholes might bend a wheel because the thin sidewall does not provide adequate impact absorption. With that visual in mind, it can be helpful to think of tires as the biggest shock absorbers (dampers) on trucks. They can work in our favor or against us. Softer, tall-sidewalls can absorb impacts and improve ride quality for one application, or reduce control and handling on another. Adjusting the pressure or changing the size can increase or decrease overall performance.
Large 37×12.50R17LT Goodyear Wrangler MT/R is only a 50 psi tire, but the tire volume makes the SRW rating 3,525-lb each. I generally prefer the handling attributes of higher psi tires on heavy rigs. This outfit is a good an example of excessive tail-swing and rear overhang, both all too common on many modern flatbed camper builds.
My dislike for huge wheels with silly shortsidewalls on four-wheel-drive pickups emanates from decades of actually using trucks for off-pavement travel instead owning them as a fashion statement. What constitutes a silly short sidewall on a four-wheel-drive depends on the diameters of both the wheel and tire, but historically an aspect ratio below 70-percent might qualify. However, the aspect ratio alone does not tell the whole story, as it is a percentage of the width. A bigger wheel and tire combination with a lower aspect ratio might still have enough sidewall to work well off-pavement, while providing superior control on-road, particularly with a massive load.
Function Over Form
There’s little doubt that the humongous big-wheel craze on pickups (20” and taller) is mostly the result of the street-truck culture, not farmers and ranchers, heavy haulers, or commercial industries. Brakes are much larger on modern vehicles, but it doesn’t take 20” wheels to clear them. My recent interest in bigger wheels with shorter sidewall rubber is for optimal chassis stability and performance with my Hallmark camper; I prefer the traditional look of more tire and less wheel.
Many late-model diesel pickups are delivered with thirty-threes mounted on 18” wheels, and have a 7.5” sidewall. (Overall diameter minus the wheel height divided by two equals sidewall height.) Increasing tire diameter to 35” on an 18” wheel produces an 8.5” sidewall, an almost 14% increase. The same 35” rubber on a 17” wheel produces a 9” sidewall, which is a substantial 20-percent increase over the stock LT275/70R18 size. Using a 20” wheel for a thirty-five brings the sidewall height back down to 7.5”; same as the factory thirty-three on an 18” rim.
People don’t complain about the stock 275/70R18E having a short sidewall. SRW capacity is a respectable 3,640-lb at 80 psi.
If you think a 35” tire is huge, think again. Most new heavy-duty Rams will fit a narrow 35” tire (LT285/75R18) on stock wheels with little or no rubbing, and only minor rubbing on the radius arms at full-steering-lock if a wider, 35×12.50R18 is squeezed onto the factory rims. Running only 35s on my fourth-generation Ram/Cummins 2500s puts me in the smaller tire club; 37s on aftermarket wheels are the popular cool choice for many.
Cooper’s AT3 XLT in 285/75R18E (34.84”) with a 129 load index can handle 4,080-lb each at 80 psi.
Are 19.5” Wheels and Medium-Duty Tires The Answer?
Some of the heavy-hauling crowd, particularly those with cab-over campers, found a solution decades ago with 19.5” medium-duty commercial tires when there were fewer tire size options. Rickson Wheel Manufacturing was founded to service this niche. The enthusiast owner started making 19.5” SRW 8-lug wheels to fit heavy-duty pickups because he was burning through sets of 16” rubber on his camper-equipped second generation Dodge Cummins turbo-diesel. This was before the excellent availability of 18” and 20” light-truck tires and wheels, which can offer up to 35% more capacity per tire than the sixteens of the 1990s.
In addition to superior load support and firmer handling provided by the much stiffer 19.5” components, there are theoretical benefits of substantially more longevity. I have yet to find a well-documented, back-to-back comparison proving similar tread design medium-duty rubber lasting much longer than a commercial-grade modern LT tire. I don’t doubt that it is possible, but show me. Medium-duty tires typically cost more, so more miles may be needed to make the modification pencil-out for those wanting to save money. Tread choices are also fewer.
In addition to limited availability of 19.5 inch wheels for pickups, and the possibly too firm load range F, G, or H construction, the biggest negative I see with medium-duty rubber are the lower speed ratings. Up to 245/70R19.5, which is only a 33” tall tire, the speed rating is a reasonable 87 mph. Moving up to a 265/70/19.5 or larger size typically reduces the speed rating to 75 mph.
Are 19.5” tires and wheels the answer for heavy pickups? They are for some heavy haulers.
There’s one area where the folks who favor 19.5″ tires and wheels and my recent interest in modern heavy-duty light-truck 20″ tires align perfectly; it’s about how they work not their appearance.
If one is going to load their SRW chassis with more than 8,160-pounds on the rear axle, the capacity offered by load-index 129 light-truck tires, super-stout and less flexible medium-duty rubber might be necessary and/or beneficial. I have read several comments online, and spoken to others who say 19.5” tires are too stiff over rough roads, both paved and not, even on heavy trucks. On unloaded rigs, the ride is sometimes described as downright jarring. Some are willing to tolerate an extra-firm ride, but is worth remembering that unnecessary roughness will be transmitted to all chassis components, potentially reducing their longevity. Surely some folks love their 19.5” tires and wheels on SRW pickups, but they appear to be a small minority.
If someone wants to lend me a set I’d be happy to bolt them on and give them a spin. My extensive heavy-duty pickup and LT tire knowledge has repeatedly convinced me that I don’t need to spend my time and money on medium-duty rubber for my pickups. Skipping the 19.5” wheels and going straight to modern, readily available twenties made more sense.
Cooper Discoverer AT3 XLT 18” vs. 20”
In typical RoadTraveler James fashion, I did back-to-back evaluation drives to observe differences between almost identical rubber wrapped around different diameter wheels. To limit controllable variables, the same manufacturer and tread design was chosen. Without this approach, carcass construction differences and other factors would unfairly skew impressions. While construction matters (continue reading), sometimes much, the goal was to test what dynamics are affected by simply changing the wheel diameter. With that established, one can then seek tire construction and/or other suspension solutions as needed for their specific application.
18” wheel on the left, 20” wheel on the right, all other specs are very similar.
The good folks at Cooper Tires, one of the few American companies still making tires in the United States, supplied the rubber to facilitate the evaluations. The redesigned Cooper Discoverer AT3 Family of Tires was introduced at the 2018 SEMA Show. It includes three distinct models targeted at specific segments of the all-terrain market. Cooper describes the attributes of these AT3s as:
Discoverer AT34S™ Severe snow rated with improved wet weather performance, snow performance, fuel economy, and with significantly improved tread wear.
Discoverer AT3LT™ and Discoverer AT3XLT™ Designed to be powerful, shred-resistant all-terrain tires. With the Discoverer A/T3™ well-known for its long-lasting tread wear and dirt road performance, the new Discoverer AT3LT™ and Discoverer AT3XLT™ tires feature Durable-Tread Technology™, enhancing durability, and enabling a best-in-class mileage warranty.
Longevity and durability has much to do with the application and duty-cycle, but Cooper has certainly upgraded and expanded the all-terrain AT3 line to cover all consumers who want this type of five-rib tire. Heavy-duty pickup owners should look at the AT3 XLT version, as it comes in the largest sizes with the highest load ratings.
Similar But Different
Because I prefer taller and narrower sizes for most conditions, I chose the 34.84-inch-tall LT285/75R18, and the 34.57-inch-tall LT285/65R20. There is very little difference in height or width between these two sizes, for all practical purposes they are the same, with the exception of the wheel diameter, which gives the twenty a much shorter sidewall. The 285/75R18 has a 8.42” sidewall, and the 285/65R20 has a 7.28” sidewall. Both sets of tires were mounted on factory Fourth Generation Ram aluminum wheels.
Both tires have a 285mm section width, but look at the tread width difference, which is noted in Cooper’s specifications.
Cooper Discoverer AT3 XLT
LT285/65R20
LT285/75R18
Load Index (SRW)
127 = 3,860-lb
129 = 4,080-lb
Height
34.57”
34.84”
Section Width
11.5”
11.5”
Tread Width
9.69”
8.9”
Weight
62-lb
60-lb
Tread Depth
16/32”
17/32”
Cooper AT3 XLT General Observation
Both sizes track straight and true, as one would expect with a five-rib all-terrain. While driving through dozens of miles in heavy rain, the AT3XLT performed fantastically, evacuating water well, a forte of a ribbed tread pattern. Siping is generous to help with all slippery conditions. Though obviously not a mudder, some light, shallow mud was handled impressively well during a weeklong autumn camping trip in remote northeast Nevada.
Unless one wants a dedicated highway offering like the Cooper HT3, the AT3 XLT is a quiet, efficient design that should yield good fuel economy. The XLT has attractive, aggressive sidewall shoulder tread that looks good and should prevent both off-pavement and curb scrubbing damage.
Sitting at 8,900’ after two days off-pavement and some recent light mud, the Cooper AT3 XLT performed well.
Test Drives
Several back-to-back drives were performed over six months. The first with more off-pavement miles was a 45-mile loop that included 30 miles of freeway, five miles of rural highway, and 10 miles of rocky dirt on the historic Henness Pass Road trans-Sierra route. When the road got rough, I continued for a few miles at full psi, before dramatically lowering the pressure at a specific point to improve the ride and traction.
Shorter 20” sidewalls are a bit less forgiving at full psi on the roughest roads, lowering pressure helps. This Cooper AT3 XLT 285/65R20 was initially tested at 37 psi, but is at 30 psi in this photo. Dropping the extra 7 psi greatly improved the ride.
Both sets of Cooper AT3 XLT tires, and other sets of rubber in our test fleet, were swapped on-and-off our 2017 Ram regular cab flatbed for comparison. Both sets of Coopers also saw some miles on our 2014 Ram crew cab.
The 20s went on a 1,000-mile vacation with my wife and our little Welsh Terrier Elsie. That trip included over 100-miles of unpaved roads, that were occasionally rocky, snow-covered, or rough washboard. I intentionally gave the 20s more time and miles as I have much experience with Cooper 18s, including the previous AT3. As of this penning both sets have seen a combined 5,700 miles.
Remote northeastern Nevada camp, during a weeklong on- and off-pavement camping trip.
There are many potential variables to putting softer or firmer tires, and taller or shorter wheels on a chassis. If your suspension is stiff or the load is light, maybe a softer tire is better, as long as it’s not overly susceptible to punctures. Softer suspension and/or huge loads may benefit from a stouter design. The bullet points below share the pros and cons of using 20” verses 18” Cooper Discoverer AT3 XLT tires for big loads on heavy-duty trucks.
20” Tire & Wheel Positives
-Substantial improvement in lateral stability from reduced body-roll/sway when compared to 17” or 18” tires of similar construction. Feels like the improvement from adding a heavy-duty rear anti-sway bar compared to the factory bar.
-Steering feel is better, tighter, and more responsive with less delay.
-Slow, mountain turns and switchbacks with warning signs are less concerning.
-Freeway hop/bed-bounce caused by concrete freeway expansion joints is reduced.
My 140.5” wheelbase regular cab is stable and controlled over most surfaces, with inherently little freeway hop compared to the 149.5” wheelbase crew cab. Mounting the Cooper AT3 XLT 20” wheels on the crew cab both firmed-up the ride as we’d expect, and noticeably reduced freeway hop.
An important safety consideration is that even if the chassis feels stable and composed enough to increase speed in certain situations, there is only so much available traction. When we use more of the total traction available, we are reducing our safety cushion, and putting more load on the tires, which causes wear and reduces longevity.
Does a 20” tire and wheel work best for your late-model truck? The answer may depend on your needs, preferences, and duty-cycle.…or does an 18” tire and wheel work better for your application? You be the judge.
20” Tire & Wheel Negatives
-Noticeably less forgiving and rougher than the 18” tire over speed-bumps and on rocky roads at full street pressure. However, when the going gets tough, reducing psi benefits all tires and sizes tremendously. To get the same ride over rocky terrain, the 20” tire liked being about five psi lower than the 18”, particularly the fronts.
-Small bumps, cracks, or holes on the roadway are more noticeable, as the tire has less ability to absorb the imperfections. How noticeable depends on the tire construction, pressure, load, and surface. With my heavy Hallmark camper, 20″ Cooper AT3 XLT, which is admittedly a softer design, never felt harsh or uncomfortable on the pavement.
Conclusion?
My 18” vs. 20” test driving quickly convinced me that with heavy loads a shorter and/or firmer sidewall that reduces some of the squishiness of a more flexible design was a positive. The biggest tradeoff is on the roughest, unpaved surfaces, which can be mitigated by adjusting tire psi and/or choosing a taller size.
With a given design like the Cooper AT3 XLT used for this comparison, the shorter 20” sidewall was also firmer and less flexible. However, if you change the tire construction characteristics, you have changed the suspension, and you have a new baseline.
Mounting the stoutly-constructed Cooper Discoverer S/T MAXX (or similar) with 3-ply sidewalls in an 18” size delivered better overall control than the softer 20” AT3 XLT. That is not a dig against the AT3, as it intentionally targets a different audience. Want or need another level of firm performance over an 18” Cooper Discoverer S/T MAXX? You can move up to one of the 20” S/T MAXX sizes. Modifications lead to modifications, and every change can affect something else.
Cooper S/T MAXX is a favorite heavy-duty hybrid/commercial traction design. Even a 1” wheel diameter difference is easy to see and feel. Both about 34” tall, 17” Power Wagon wheel (left), and forged Big Horn 18” wheel (right).
My travels include more off-pavement miles than many, so I am still evaluating where I want to make my long-term compromises, but like everyone, most of my driving is on good, paved roads. Currently I’m preferring 20″ tires for my flatbed camper outfit. My tire and suspension evaluations are continuing, and you can find additional information about these and other subjects here on RoadTraveler.net, or on Instagram, @RoadTraveler.
The sign says, “TRAILERS NOT ADVISED BEYOND HERE”. My camper is frequently off-pavement, but like nearly everyone, most miles are on blacktop.
At the SEMA Show a few years ago TUFTRUCK introduced heavy-duty rear springs for the 2014 and newer Ram 2500 trucks. They had already been making replacement coils for the front axles of Ram trucks and other brands for several years.
TUFTRUCK is a brand of McAllister Industries out of British Columbia, Canada. This company has over 100 years of manufacturing experience, making leaf and coil springs for everything from light trucks up to huge mining equipment from quality American steel.
The TTC–1225 springs fit the 2014-and-newer, Ram 2500 trucks with coils atop the rear axle and cost about $425 a pair. They have a spring rate of 438 pounds-per-inch, and according to TUFTRUCK they add an additional 500 pounds of capacity. The chart below tells how much beefier the TUFTRUCK coils are compared to the stockers, and the differences are easy too see, feel, and measure.
Beefy Canadian aftermarket heavy-duty replacement rear coil springs.
TTC-1225 vs OE Coil
TUFTRUCK TTC-1225
OEM 2014 Rear Coil
Height
18”
17.75”
Diameter
8”
7.5”
Material Thickness
0.93”
0.86”
Weight
35-lb
24-lb
Left: TTC-1225 Right: OEM Ram 2500 rear coil.
Installation And Road Tests
Swapping the rear coils on heavy-duty Rams is a simple job for the mechanically inclined and experienced; it is much easier than removing and replacing long, heavy, and awkward leaf packs. I did the project by myself, without a vehicle hoist and with zero cursing. If I had been removing-and-replacing leaf springs, particularly solo, there certainly would have been busted knuckles and profanity.
Ran this setup for many thousands of miles on two 2500 trucks; OE coils and Air Lift 1000 springs.
After chocking the tires on the front axle, lifting the rear of the truck, supporting the frame with jack stands, disconnecting the rear shocks and body-roll bar, and removing the rear wheels, the axle was drooped as far as practical to make the coils loose enough to remove. (Remember to insure you’re not pulling on brake or ABS lines.) Because the TUFTRUCK coils were just fractionally taller, and drooping the axle provided plenty of access, no spring compressor was needed. I spent much more time making measurements, videos, and photographs than doing mechanical work.
Doing the spring R&R was incredibly easy.
To make a direct, back-to-back comparison of the factory coils and the TUFTRUCK TTC-1225, the Air Lift auxiliary springs were deflated (to zero) before I drove a 15-mile test loop over a mix of city streets, rural highways, and interstate freeway. This type of repeatable initial testing, combined with notes made during the drive, helped document performance differences with an eye on reducing the effects of faded memories and subjectivity.
After installing the TTC–1225, there was a noticeable and substantial improvement in stability, control, and spring rate compared to the OEM coils. The stouter and fractionally taller TTC-1225 coils produced a 3/4” height increase measured at the bottom of the hitch receiver, with my Hallmark camper mounted (without water or gear).
TUFTRUCK’S TTC-1225 rear coils installed and ready for work.
Shortly after the installation I made a 1,000 mile roundtrip over the north-south length of Nevada, to buy a new Welsh Terrier puppy, our first travel-size dog. Then a 1,500-mile round trip to the Southwest in May. The TUFTRUCK rear springs are working well, and I’m glad I added them. Stay tuned, there are additional rear suspension upgrade editorials coming.
Our new six-month-old Welsh Terrier puppy we named Elsie Desert Rose. She fits well atop the center console in the regular cab camper truck.
It’s not news that oil and water don’t mix, but if it happens inside a driveline component and you are unaware, the results will eventually be catastrophic. The factory differential breathers on late-model Rams are raised slightly, to near the top of the tires, which is good enough for most folks. Hopefully that would be plenty for me too, as I’m not a fan of playing in deep water or soupy mud. However, it has happened before, including an unfortunate loss of forward progress that lasted hours. Being an ounce-of-prevention guy, I chose to be proactive regarding keeping the H2O out of my gearing lubricants.
For decades I have extended the breathers for driveline components using small, inexpensive air or fuel filters, but a few years ago ARB introduced a most tidy aftermarket solution that I’ve used since. Employing the same filter as their 12-volt air compressors, ARB makes a neat aluminum manifold into which their filter and extended vent lines attach. Vent tubing and fittings are also supplied, and the kit retails for $72.
Aluminum manifold block and air filter.
For the 2017 Ram/Cummins 2500 Pack Mule with Hallmark flatbed camper, I mounted the ARB manifold at the top left of the engine compartment, similar to my 2014 Ram, but I drilled a new hole this time. Using the OE rubber vent hose as my start, the rear axle breather line was extended using ARB’s plastic vent tubing, first inside the Hillsboro flatbed frame, then along the truck frame under the cab and up into the engine compartment. The front differential vent was extended the short distance from near the left front shock, and the transfer-case breather was raised from atop that gearbox into the engine compartment. A trained eye might notice the ARB Differential Breather Kit as aftermarket, but it’s very tidy and clean.
Low, factory vent hoses/caps can get clogged with goop, snow, or ice, causing housing pressure that can lead to leaks. Mounted in this spot, the filter just clears the closed hood.
