Wheel Basics
Most Galleria RVs start with a base Sprinter chassis and are up-fitted into an RV. For extra cargo carrying capacity (CCC), a dual rear-wheel (DRW) van, affectionately known as a dually, is commonly used. The wheels delivered with the base chassis are Original Equipment Manufacturer (OEM) standard factory steel rims with Continental tires. When ordering a Galleria, you have the choice of standard steel rims, alloy rims, or Alcoa rims.
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Rims
The rim size for a Sprinter 3500 is 16 inches diameter x 5.5 inches wide with 6 mounting holes on a 130mm bolt circle. The center hole is 6.33 inches diameter. Rims are tubeless, and the steel wheels have a .453 diameter hole for the valve stem. (We need to verify the stem hole diameter for alloy rims…)
Steel – Steel rims come standard on Sprinter RVs, and there is no extra cost for keeping them. Steel rims make it easy to rotate tires and use the same size lug nuts and wrench sockets on all wheels. There’s very little difference in performance between steel rims and alloy rims. They are more durable than alloys and won’t crack from an impact.
Disadvantages – at 27 lbs, they weigh a little more than alloy rims, and if not maintained properly, they can rust.
Alloy & Aluminum Rims – People prefer alloy rims primarily to give their vehicles a premium appearance. What’s a few more dollars here and there when you’re paying that much for a camper van? Alloy rims weigh less per wheel than steel since they are made of an alloy of aluminum, magnesium, and nickel. This implies that they accelerate and brake with less rotational mass. Sprinters don’t really live up to their name, and it’s unlikely that anyone would notice any differences in “off-the-line acceleration” when drag racing an Amazon van.
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Hub Centric / Lug Centric
The terms “hub centric” and “lug centric” describe how a wheel is centered on your axle. The center hole of hub-centric wheels is known as a hub pilot and is tightly machined to perfectly match the hub of the vehicle. This is the most precise approach to attaching the wheel because it enables the wheel to be centered on the hub. The OEM steel wheels made for the Sprinter van and Alcoa rims are a hub-centric design. The OEM steel wheel lug nuts use a 19mm socket while the Alcoa lug nuts have a cap over the lug nut which would require a 22mm socket or 19mm if you remove the cap.
Some aluminum aftermarket rims are lug-centric, centering on the hub by utilizing the lug holes. As a result, the wheel’s hub bore can be made larger by the rim maker, enabling the wheel to fit a wider range of vehicles. The drawback is that a special centering adapter is required for wheel balancing and may not be available at all tire stores. Shown here is the lug nut for the CWS (Custom Wheel Solutions) rim option from coachmen. It uses a 22mm socket.
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Valve Stems
Valve stems are available in several choices and have a price range anywhere from a few dollars for rubber stems to $160 for a full set of metal dually stems. Consider metal if you’re installing a TPMS (Tire Pressure Monitoring System) on the valve stems. Because of the centripetal forces resulting from driving at 70 mph, rubber valve stems can flex or rub against the edge of the rims and wear through, causing air pressure loss.
(We have decided to change back to OEM steel rims on our Galleria and may need to install the $160 set because the $6 metal stems from the auto parts store don’t fit.)
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TIP#153: How to change a wheel
Note: If you are going to change a tire yourself, be aware they are approximately 65-70 lbs. (Michelin Cross Climate is 40.41 lbs, and a steel rim is 27.98 lbs.)
With both rear doors open, use the flat-blade screwdriver from the tool kit under the passenger area floor to remove the two square tabs on the door sill.
Remove the wheel lug wrench and handle from the tool kit under that passenger floor mat.
Turn each of the bolts 20+ times counterclockwise to unlock the safety hooks holding the tire cage.
Remove the jack from the compartment on the passenger step and assemble the 3-piece handle.
Using the handle for leverage, lift the spare tire cage and unhook the supporting hooks under the van.
The passenger side of the rack has a tube to fit the jack handle, so you can carefully lower the cage and wheel. (It would have been helpful to have a tube on the other side of the rack as well, which sounds like a future welding project.)
There are several jacking locations around the frame that the jack can seat into to avoid slipping off. The picture shows the front passenger-side jack point located forward of the wheel.
The jack can be extended by unscrewing the top pad; however, it will still be too short to lift the van. I suggest carrying a couple 2x8x12 boards to support the jack on soft ground. RV-leveling blocks may also work.
Using a heavy breaker bar, loosen the wheel lug nuts before jacking the wheel all the way off the ground.
NOTE: Alum wheels use a 22 mm socket, and steel wheels use a 19 mm socket.
Once the lug nuts are loose, jack the wheel off the ground and replace it with the spare.
TIP#157: Instead of trying to lift the spare tire onto the studs, raise/lower the van with the jack to gently finesse, align, and hook the tire onto the studs. Use the jack handle to leverage the wheel if needed. (Save your back!)
Install the lug nuts and tighten them to a torque of 133 lbf-ft (or really, really tight). Tighten nuts opposite each other in a zig-zag pattern to even out the stresses.
TIP#218: Some experts recommend using thread anti-seize on *stud threads only*. Use it very sparingly, and DO NOT GET IT ON THE NUT FLANGE surface or rim surface. If you are using anti seize, reduce the torque to 100-105 lbf-ft.
(Note: I have never used it, so do your own research on this.)
Drive the van for approximately 5 minutes to seat the rim on the hub and double-check the torque of the lug nuts again.
TIP#103: Lug Wrench – shown above: Amazon: 23″ Universal Extended Lug Wrench, 4 Way Lug Wrench with sockets. https://www.amazon.com/gp/product/B08CR7K88Q/
TIP#158: Torque Gauge – Instead of carrying a separate torque wrench, this handy adapter fits between the breaker bar and socket and can be set for a specific torque. When you reach the specified setting, it will beep and flash its LEDs.
Amazon: AC Delco ARM602-4A 1/2” (25 to 250 lbf-ft.) Heavy Duty Digital Torque Adapter
https://www.amazon.com/dp/B07DV33XJ5
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Lug Nuts
TIP#097: NOTE: A steel rim (like the spare) uses a different style of lug nuts than the CWS alloy rims.
Nut Part Number for the steel wheel lug nut: MB 000-990-53-53 $8.00 each
– Steel: 19mm hex socket wrench
– Aluminum: 22 mm hex socket wrench.
Stud Threads:
– metric M14 X1,5 thread
– 6 studs per axle
– 130mm long studs in front
– 205mm long studs rear for the dually.
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Lug Bolts
Older Sprinters and the 2500 use bolts instead of lug nuts. This makes changing a tire a little more challenging since you need to hold it in position, align the holes, and insert a bolt.
Our Great West Van was like this, and we picked up a wheel guide pin. It temporarily screws into an upper bolt hole, and you can lift the tire to hang on the pin and then insert some of the other bolts. Finally, replace the pin with a bolt, and you are done.
WARNING: One area of confusion when looking up Sprinter van lug nut torques for alloy vs. steel: The torque for the bolt is 177 lb-ft, which is different from the lug nut’s torque of 133 lb-ft since it has more threaded contact area.
Torqueing a lug nut to 177 lb-ft can fatigue and break the wheel stud.
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TIP#174: I didn’t know that:
Torque – You may wonder why the torque on the nut is lb-ft vs. ft-lb. The Society of Automotive Engineers (SAE) lists the “pound-foot” as the official unit of measure for torque. Since the abbreviation for foot is the same as for feet, a lb-ft could easily be referred to as pound-feet and is sometimes displayed as lbf-ft. The metric system uses Newton Meters for measuring torque.
Work – Foot-pound (ft-lb) is a measurement of work. Work is the measurement of force over a given distance. Thus, one foot-pound is the amount of energy required to lift a one-pound object one foot vertically. When James Watt determined that a horse could lift 550 pounds at a rate of 1 foot per second, he declared it 1 horsepower.
You will still see many places where torque is shown as ft-lb. I had to go back and edit some of the pages on the website as well. 😉
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Tire Sizes and Brands
New Sprinters are delivered to Coachmen with steel rims and Continental LT215/85 R16 tires. If you have chosen the optional aluminum rims, the Continental tires are removed and installed on the aluminum rims.
By far, the most recommended replacement tire by other Sprinter owners is the Michelin Agilis CrossClimate LT215/85 R16 115/112.
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TIP#189: Tire Codes
LT – The first letters can be “P”, “LT”, “ST”, or no letters.
P = Passenger, LT = Light Truck, ST = Special Trailer for utility trailers to 5th wheels.
215 – Next number is the width of the tire measured at the side of the tire in millimeters. (215 mm = 8.46 inches wide)
85 – The number after the slash is the aspect ratio percentage (height) from the rim to the road. 85 means 85% of the width (215 mm dimension * 85% = 182.75 mm = 7.19 inches).
R – indicates a radial-ply tire, or it could be a “D” for bias-ply construction.
16 – The rim diameter is next, and for some strange reason we switch to inches. 16-inches-diameter rim.
115/112 – The last set of numbers refers to the tire’s load index, which is how much weight the tire can handle when inflated properly. Using a chart indicates 2,679 lbs – 2,469 lbs per tire.
R – Michelin CrossClimate tire has a final letter “R” for a speed rating, indicating the tires are rated for 106 mph max. I guess we won’t be attempting any Sprinter speed records on the Bonneville Salt Flats.
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Tire Date Code
Tires should be replaced after 7 years, regardless of how good they may look. So, how old are your tires? The TIN (Tire Identification Number), which starts with “DOT” (Department of Transportation), is a 12–13-digit code. The first two numbers identify the tire manufacturing facility, followed by the tire size and internal manufacturer codes. The date of manufacture is indicated by the last four digits. The first two of these numbers represent the week in which the tire was manufactured, and the last two of these numbers represent the year. (For example, 2022 denotes week 20 of 2022.)
NOTE: The 2500 sprinter bolt torque is 133 lb-ft for 15-inch rims and 177 lb-ft for 16-inch rims. (Double check my numbers in your owner’s manual.)
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Tire Pressure
Tire pressures are usually displayed on a label on the driver’s side door jam placed there by the RV manufacturer. The pressure is displayed in PSI (pounds per square inch) and is the pressure when the tires are cold. The maximum tire pressure is printed on the side of the tire, but this is not the pressure you should be using.
The amount of tire pressure required in each tire is determined by the weight of the fully loaded vehicle, which includes passengers, cargo, fuel, and water. Pressures can vary between tire manufacturers and the type of tire. To find the exact pressure you should have, you will need to have each axle weighed and look up the weight on the manufacturers’ reference tables.
Tire inflation pressures should be maintained across an axle at the same inflation pressure, especially for dually sets. The maximum allowable difference between tires across an axle is 5 psi. For example, if the recommended tire pressure across a rear dual axle is 65 psi and one tire only has 44 psi, it is considered to be flat.
TIP#205: Tire Pressure Labels – A mind is a terrible thing to waste. I’m beginning to get to that age where I get up to do something, and half way there, I’ve forgotten why I got up. I think it is called OPD (Old People’s Disease) :-). When checking tire pressure, I check the pressure label on the door, and by the time I get to the rear wheels, it’s back to the door to look again. My solution is to add stickers so I don’t need to go back to the door so often. Now if only I could remember where I left the pressure gauge.
PS: Our Tire Pressure Monitor System (TPMS) is more trouble than it is worth.
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Tire Pressure Monitor System
There are two basic types of TPMS. An internal sensor that is strapped to the inside of the rim and external sensors that screw onto the valve stems. As mentioned previously, valve stem-mounted sensors should not be used with rubber stems due to the flexing of the stem. Both systems transmit to a receiver display on the dash. If the signal is receiving interference, a repeater may be needed. Some systems can even display pressure from a toad (towed car) or trailer.
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Tire Temperature
As mentioned previously, tire pressure is measured when tires are cold. So, how hot can a tire get? Most experts consider 195 degrees Fahrenheit as the maximum temperature. Beyond that point, the temperature will start impacting tire life. At 250 degrees, a tire will start to lose structural strength and could begin to delaminate and make a “road gator”. (A road gator is a slang term for a delaminated piece of truck tire tread on the side of the road that looks like an alligator’s back.)
Tires can become overheated due to low pressure, weight overload, dragging brake pad, or bad wheel bearing. Tires heat up due to friction from the flexing of the tire. Low pressure can cause additional flexing and overheat the tire. A simple rule of thumb: tire pressure will increase by 2 psi for every 10-degree increase. Normal highway driving can increase the temperature by 50 degrees and the pressure by 10 to 15 psi. In a dually configuration, low pressure in one of the pairs can cause the good tire to overheat because it is now carrying a double load.
A simple way to measure tire temperatures is with a laser thermometer. They are also very handy for other uses around the RV. Some TPMS can alert you to high temperatures as well as pressure issues. They have a temperature alarm, usually set at 158 degrees.
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Wheel Alignment
The best way to eliminate tire wear is to not drive the RV. 😉 Other than that, poor alignment is a leading cause of excessive tire wear. Front-end alignment ensures the wheels are adjusted to the proper angles. It is suggested that you get a front-end alignment approximately every 50,000 miles or when you observe uneven tire wear, pulling to one side, or tire vibrations. A front alignment includes a camber, toe, and caster adjustment.
Camber – is the angle of the tires with respect to each other. Negative camber means the bottom of the wheels angle outward. Positive, they angle inward.
Judging from the many YouTube videos available, adjusting the camber can be tackled by a backyard mechanic using a simple metal bar and a digital level (like the Klein Tools 935DAGL Digital Level Angle Finder). …Future tutorial…
Tire slip plates can be constructed from a couple metal plates with grease between them, or one mechanic used a large plastic garbage bag folded several times and placed under each front tire. Camber bolts can be installed if you want to fine-tune the camber angle.
Mercedes Camber Bolt part number: A 002 990 86 00 Dealership=$80 each, web=$56+.
Toe in and toe out are easy to visualize. Looking down on the tires, are the fronts angled together or apart? This angle can be adjusted by the track rod that connects the tires together.
To measure the toe dimension, lay a metal bar against the outside of each front tire, about 10 inches above the ground, and measure from tire to tire at the front and back of the tires. If the measurements are the same, the toe angle is 0 degrees.
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Storage
Storing an RV for more than a few months, tire care and protection are important for the life of the tire. Tires degrade due to UV, ozone, weather, and storage conditions.
TIP#280: Storage Tire Pressure – To store the RV, unload the vehicle so that the minimum weight will be placed on the tires. Inflate tires to the recommended operating pressure plus 25% (do not exceed the max pressure printed on the tire). Store away from electric generators or transformers that produce ozone, and place a barrier between the tire and the storage surface. Suitable barriers include plastic, plywood, cardboard, or rubber floor mats. For outdoor storage, cover tires to block direct sunlight and ultraviolet rays.
If storing for more than 3 months, drive the vehicle for an hour at highway speeds once a month to prevent cracking in the sidewalls as well as “flat-spotting” from the prolonged strain of the sidewall and tread deflection.
303 Aerospace Protectant is ideal to use on your tires and engine hoses and belts.
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Rotating Tires
Tires do not need to be rotated unless they are wearing unevenly from axle to axle or side to side. When there is irregular wear, rotate the tires so they turn in the opposite direction. Rotating tires can become complicated by having a mix of different types of tire rims. Our Galleria has aluminum rims and steel rims on the inner duallys and spare, which makes it difficult to rotate them around. This is another reason we are converting to all OEM steel rims.
NOTE: Some passenger cars have directional tires that have rotation arrows on the sidewalls. They must always be mounted with the arrows in the correct direction. LT (light truck) tires, like the sprinter, are non-directional.
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Nitrogen Fill
For many years, people have been debating whether there are any advantages to nitrogen tire inflation. 78% of the earth’s atmosphere is made up of the dry, inert gas nitrogen, which has no ability to hold onto moisture. While using 100% nitrogen systems is advantageous for big off-road earthmover tires and aircraft tires, it is typically challenging to identify any benefits for recreational vehicles.
In a Consumer Reports research, tires were inflated to 30 psi with nitrogen and another 30 psi with compressed air, then left outside for a year in the elements. The nitrogen-filled tires lost 2.2 psi on average, compared to 3.5 psi for the compressed air tires.
The claim is that nitrogen molecules are larger and have a more difficult time escaping through the microscopic spaces between the rubber molecules. Nitrogen is also labeled a “slow” inert gas and is non-reactive with other materials. Oxygen is a “fast” active gas and reacts with many materials through oxidation,” for example, the rusting of metals.
While there are no disadvantages to filling tires with nitrogen, the benefits are minimal, and some tire shops charge as much as $5 just to top off a nitrogen-filled tire. The low moisture content of nitrogen may offer an advantage over compressed air. Tires filled with nitrogen typically use a green valve cap.
One question I’ve always had: If the oxygen molecules are small and pass through the rubber and nitrogen doesn’t, over time, wouldn’t there be only nitrogen left in the tire after the oxygen has passed through?
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Balance
Uneven tire wear and vibration in your steering wheel, floorboard, or seat can signal it’s time for tire balancing. In order to identify the source of the vibration, consider the following factors to assist the servicing dealer:
• Road conditions when the vibration occurs.
• Vehicle speed and engine rpms when the vibration occurs.
• Where the vibration seems to be coming from (front or rear of the vehicle).
• Frequency of the vibration (does it phase in/out, or is it constant?).
NOTE: The CWS (Custom Wheel Solutions) aluminum rims from China installed by Coachmen appear to be difficult to balance. They are lug-centric and require a special adapter to balance the wheels. Many owners have reported vibrations around 60–65 mph. Both of our Galleria vans had the same issue, which is another reason we are switching to the Mercedes OEM steel rims as the tires need replacing.
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Leveling Blocks
When using blocks to level an RV, extreme caution must be taken to make sure the tires are fully supported. The weight on the tire should be evenly distributed on the block, and in the case of duallys, it should be evenly distributed on blocks for both tires.
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