Category Archives

UPS delivered the wheels and tires this morning, and I threw them on the truck over my lunch break. 2″ in the front, measured from the ground to the wheel wells. So far I’ve only driven them around the block a couple times, but they handled well. Towing the fifth wheel will be the real test.

The shipment was missing one of the center caps (which I left off the rear driver’s side of the truck, for now) and the lug nuts, but I was able to reuse the lugs from the Vision wheels. They have shipped out replacements.

Back in July 2016, I installed Michelin XDS2 tires on Vision 81 wheels on my truck. The tires are commercial, 19.5″ tires that have significantly higher load carrying capabilities and stability than offered by conventional passenger truck tires. To that effect, they’ve been excellent and were well worth the money. If all I ever did was tow, and rarely used my truck unloaded, or never longed to leave the pavement, they would be the perfect tire.

However, 19.5″ tires are full of downsides that have slowly become more and more apparent to me.

• They ride rough and jerk you around because they don’t absorb road anomalies. This is due to both sidewall construction (extremely stiff) and high pressure. My rear tires are almost always at or above 90PSI. If not for the Kelderman suspension, they would be unbearable for my wife and uncomfortable for me. Now they’re just somewhat uncomfortable for both of us.
• They’re loud and getting louder.
• 245 tires are narrow, which I find somewhat unappealing, and they track ruts from large trucks quite badly.
• You can’t air them down. They require something like 70PSI just to keep the bead, which is designed differently on half-size tires than passenger tires. This means you can’t reduce pressure to improve ride quality, and means you cannot air down for more traction off pavement.
• Nobody wants to work on them. This didn’t sound like a big issue, but the only places that want to work on these tires are commercial shops who don’t have the proper equipment or finesse to work on aluminum wheels without damaging them. Or at least in my experience. As they age, this does become an issue as they wear and fall out of balance. This also makes them difficult to find, if a replacement is needed.
• The tread compounds are very hard and, while they wear great, that means that you have less overall traction in lots of situations. On a slick boat ramp, for instance, I seem to have a harder time finding traction than trucks running LT tires, regardless of technique. Traction, in general, has gotten quite a bit worse over the last two years, despite a lot of tread remaining.
• They are limited to 75mph, where speed limits around here are 80-85mph.
• TPMS sensors don’t work with them – the signals cut in and out and generally don’t work.
• The selection is extremely limited compared to passenger tires, and they are far more expensive. These cost nearly $500/ea.

I’ve looked numerous times over the last year or so for a light truck wheel and tire combination that would provide the load carrying capacity I need with a decent safety margin left over. With a rear axle weight of approximately 7400lbs, that means I need a tire capacity of 3700lbs, and at least a 10% margin of safety on top of that to address my concerns. That means that each component needs to be rated for 4070lbs.

I’ve seen quite a few discussions on duramaxforum.com about Cooper Discoverer STT Pro tires lately, with good reviews referring to them as a combination of nice ride quality and road manners, good off-road capability, and towing stability. They’re a MT tire which generally would have led me to steer clear of them for towing, but enough reviews have convinced me otherwise. So starting there, I looked up the specs and found that I need a 295/70r18.

The tires are 34.49″ tall, compared to my current 33.60″ tall tires, and 12″ wide compared to my current 9.7″ tires. They’re a little under an inch taller but quite a bit wider, which means I may have to make some adjustments to my suspension to make them fit nicely. Fortunately, I have plenty of room for adjustment there. They have a load carrying capacity of 4080lbs, which is over my target of 4070lbs, though not by much.

Cooper Discoverer STT Pro Tire

Wheels on the other hand, were extremely difficult to find, and it took months for me to stumble across one. The majority of aftermarket 18 or 20″ 8×180 bolt pattern wheels are rated for either 3500, 3525, 3640, or 3700lbs. None of those meet my requirements. The factory 18s (which I never had, since my truck came with 20s) are assumed to be rated for the tires that come on them,  3580lbs. For the longest time, I found no options aside from the oddball 3800lbs wheel above those figures. Last night, looking again, I stumbled upon a wheel with a 4500lbs rating.

That means that the tire, if I were to go with this setup, would be the limiting factor at 4080lbs, providing me with a rear axle capacity of 8160lbs. That’s a good bit short of the 9000lbs that the 19.5″ tires provide me, but still provide a 10% margin of safety even with the heaviest load I carry, and alleviates most or all of the bullet points listed above. The wheel is definitely not one I would normally go for: it has fake beadlocks and only comes in matte black. Black as a color is great, but not on wheels. That’s a common color nowdays, but I think that black is terrible on wheels as they tend to get lost in the tires, especially in dim lighting. Second, I only want beadlocks if I actually have beadlocks – I don’t have much appreciation for fake, non-functional gear like that. Asking around, though, the consensus is that most of my friends think they will look great. And I prefer function over form, so…  I opted to go for it.

Method Racing 305 NV HD wheel, rated for 4500lbs

I looked all over the Internet for them, but the best deal was close to home, at Discount Tire. In fact, the wheel is backordered everywhere and that is the only place that I could even find them. I ordered them online and will have them delivered to my door, since they don’t have any in stock in Texas (nearest are in St Louis, I believe they said over the phone).

I hate that you can’t try before you buy with things like this – I’m not sure how stable or comfortable the ride will be when towing the RV, which is the ultimate test. But I did speak with someone who runs the truck, with the same size tire, in Cooper S/T Maxx form (which is similar in design, and by the same manufacturer), and a 7440lb rear axle weight on factory 18″ wheels (taking his chances with those), and he claims to be very happy with the setup.

I will have to put them on and go through a little trial period, but if all goes well I will be putting my 19.5″ set on the market to make some of my money back. They have been great for towing and provided me with a lot of confidence and peace of mind when running heavily loaded, but other options are available now that claim to address our needs without all of the gotchas. I hope these work out and I can find a new home for the 19.5s.

In a previous post, I moved my air compressor and tank from where the spare tire would sit, into the truck bed, in order to allow us to carry a spare. It looked like this:

Previous to that, I had them mounted where the spare tire was, like this:

A couple of weeks ago, I went to Home Depot. As  you might expect, having a large obstruction like that, plus the hitch, made it really difficult to get the large parts (two doors, one with a full threshold) I brought home into the truck. I pulled the hitch for another project (details on that soon), so decided to move the air system to a less invasive location. I removed it with no real plan, leaving the truck effectively disabled in the process.

After a couple hours of trying to jam the components in various locations under the truck, I eventually came to the conclusion that I wasn’t satisfied with the fit and mounting any place under the floor. The best place to mount the tank would have been to the frame, under the passenger rear door, but that would have required either really long bolts that reach through the frame or tapping bolts from the tank side without backing nuts. I already have enough holes in the frame, with the air suspension and hitch rails, and opted not to add more. Now, I’m just adding more to the bed.

Finally, I decided to shove the toolbox over a bit and wedge the tank between it and the side of the bed. The tank was full, so I used a 3′ crow bar for leverage and a bunch of shoving, to get it to move into place. Then I drilled and used new 3/8-16 stainless bolts to anchor it. They’re a big improvement over the zinc junk bolts initially used. Then, I used the same kind of bolts for the air tank. After playing with ways to mount the compressor box, I decided to take it out of the box and mount it inside the toolbox. This is what I came up with:

The air dryer is mounted to the box, as low as it can go with all mounting holes being used. There is barely enough room to close the tonneau, but it works.

The compressor and electrical components wiring.

Only the compressor, air dryer, and a few hoses are exposed to the elements. All of the wiring is inside loom.

It’s been a while since I’ve last posted, and we’re out enjoying a stay at a RV park, so with the welcome downtime, I decided to post an update. I’ve made several small adjustments to the truck, and a few major ones, since last posting.

Among those changes were tuning the engine and transmission, and changing the fuel pump from a CP4 to a CP3 unit, which is much more reliable and doesn’t grenade when it fails, taking out the entire fuel system. There is a lot of information to cover about those upgrades, so I’ll save them for another post one of these days. In summary, though, I swap out tunes depending on what I am using the truck for, and have about 400rwhp for towing with some towing-specific parameters (“heavy tow”) and a 550rwhp tune I drive daily with – the tunes burn clean, with no black smoke (maybe a tiny bit for a fraction of a second at wide open throttle) and are a great improvement over stock. Those changes took about twenty hours to complete, mostly due to the complexity of the fuel pump swap. The mods are listed over on the Our Rig page, in the Engine & Performance section.

The truck is filthy now, as we’re camping and tracking mud in and out of the truck, and the dogs have shed all over it, but I did purchase new floor mats. I’ve had WeatherTech liners in the past, which are considered the best of the best, but wasn’t real happy with them and wasn’t sure I wanted them for this truck. I looked at the Husky liners but wasn’t terribly impressed with them either. I ended up buying the Aries Styleguard mats, which are amazing. Here is the driver’s seat floor mat:

The driver’s mat is the only one I wasn’t happy with as they shipped. The mats are all designed for specific make/model vehicles, but the fitment of the grommets that hold them wasn’t right. They didn’t grab onto the factory pieces and floated loosely in the floorboard. I ended up swapping the OEM grommets from the factory mats onto these, which took just a couple minutes to do but yields much better results. These don’t come up as far as the WeatherTech or Husky mats, but come up far enough, and have full coverage under the gas pedal as well as over the door jam, and have a very premium feel to them. The backing is almost like velcro, and seems to work better than the underside of the WT or the sharp plastic cleats on the Husky mats that tend to damage carpet over time.

Also, I moved the aux light and air bag switches out of the path of my legs, in case of an automobile accident. They fit really over the bin on the wall of the center console.

The new device under the grab handle is a Edge Insight CTS2, which is essentially a bunch of digital gauges to let you know where various parameters of your vehicle are sitting. It has some accessories you can add, such as an external EGT probe, which I opted for. I added the probe pre-turbo on the passenger side exhaust manifold, which required drilling and tapping.

You can see the back mat here, which is full coverage including under the seat. I added Du-Ha tool storage under the seat, which helps organize my mess and allows me to reclaim the floor space that was taken up by my Makita tool bags sitting in front of the seats.

With the seats down, I have fully functional back seating now and manageable storage.

For the outside of the truck, I decided to try adding some in-channel EGR visors. Driving with the windows down on this truck is a pretty loud and annoying experience, and I’ve never had them before, so I figured I’d give them a try. They really seem to work well, and look nice. They are the SlimLine series, and the install took less than ten minutes. I read that the OE visors they sell are rebadged EGR, and that played a role in my decision to purchase these over the WeatherTech ones.

Last, I lowered the front end of the truck approximately two inches to try and ease suspension wear and increase fuel mileage. I had to get an alignment afterwards, but aside from that, there is little to the process (just turn the torsion bolts). On this trip, we have averaged 9mpg with the trailer and 17.5mpg unloaded according to the DIC. My speedometer seems to be reading about 7% low, something I need to contact my tuner about, which means my mileage may be up to that much higher, assuming the DIC is close to accurate.

I had to move some wiring and airlines out of the way, cut the heat shield, and hand guide it into place to clear everything which almost makes it a two person job to get up there, but I now have a spare tire.

I wasn’t thrilled with the stability of this setup, so I fabricated a mount to hold the back of the compressor box to the side of the pickup bed as well, so it’s now mounted to both the bottom, wish six bolts, and the side, with two.

I spent most of yesterday evening relocating the air compressor, dryer, and 3 gal tank to the bed of the truck. I had to fabricate some mounts but didn’t have many scraps to work with, so they didn’t turn out very pretty, but they’re functional and I can always replace them later.

Clearance should be okay with the fifth wheel, but I need to test it to be absolutely certain.

The underside of the truck used to look like this:

But now has what I believe to be room for the spare tire:

I’m a little concerned that the sway bar won’t clear the spare tire, but think that, in the worst case, I can probably let the air out of the spare tire to make a little extra room, and air it up if needed with the onboard compressor.

Also, I added this little switch panel for my front and rear light bars, which gives me two spare switches for future accessories: