RV tires are complex. Understanding how they operate and how best toÂ maintain them will help you keep your motorhome in safe running condition. If a tire goes down from improper air pressure or maintenance, so does the RV and the enjoyment of theÂ trip.
Tires are composed of various types of material and rubber compounds, including
performance properties essential to the proper functioning of the tire under various
conditions. These properties evolve over time. For each tire, this evolution depends on
many factors, such as weather, storage conditions and other conditions of use the tire is
subjected to throughout its life.
That is why, in addition to regular inspections andÂ inflation pressure maintenance by the owners, it is recommended that RV tires, includingÂ spare tires, be inspected regularly by a qualified tire specialist, such as aÂ Michelin RV tire dealer, who will assess the tire’s suitability forÂ continued service.
RV owners are strongly encouraged to be aware not only of their tires’Â visual condition and inflation pressures, but also of any changes in dynamic performancesÂ such as increased air loss, noise or vibration, which could be an indication that the tiresÂ need to be removed from service to prevent failure.
It is impossible to predict when tiresÂ should be replaced based on their calendar age alone. However, the older the tire, theÂ greater the chance that it will need to be replaced due to the service-related evolution orÂ other conditions found upon inspection or detected during use. While most tires will needÂ replacement before 10 years, Michelin recommends that any tires in service 10 years orÂ longer from the date of manufacture, including spare tires, be replaced with new tires as aÂ simple precaution, even if such tires appear serviceable and even if they have not reachedÂ the legal-wear limit.
For tires that were on an original equipment vehicle (for example,Â acquired on a new vehicle), follow the vehicle manufacturer’s tire replacementÂ recommendations when specified (but not to exceed 10 years). The date when a tire wasÂ manufactured is located on the sidewall of the tire. RV owners should locate the DepartmentÂ of Transportation, or DOT, code on the tire that begins with “DOT” and ends with the weekÂ and year of manufacture. For example, a code ending with “0304” indicates a tire made in
the third week of the year (January) in 2004.
SELECTING REPLACEMENT TIRES
One of the most important equipment purchases any RV owner will make will be tires. If theÂ consumer obtained good service with the original set of tires, chances are they were
matched well for the RV’s weight needs, the RV type and the area of driving. Should the RV
owner choose to replace his tires with another size, it is important to be very careful
with this selection. There are some basic areas of concern, such as the load rating of the
new tire, the overall diameter of the tire for vehicle clearance, speedÂometer reading and
wheel width. There is also the matching of the tires to the dual wheel offset for the dual
spacing clearance and the load rating of the wheel.
For example: Buying a tire with aÂ higher load rating that might require 105 psi would be inappropriate if the RV wheel isÂ limited to 80 psi. Also, be sure that the wheel width is compatible with the new tire size;Â doing otherwise is dangerous. Consult the vehicle manufacturer for wheel specifications.
THE IMPORTANCE OF TIRE PRESSURE
After choosing the best tire for aÂ motorhome, the most important factor in maintaining the life of RV tires is making sureÂ they are always properly inflated. Incorrect air pressure for the weight of the vehicle isÂ dangerous and could cause such situations as premature wear, tire damage or a harsher ride.
An under-inflated or overloaded tire will build up more heat that could go beyond the
endurance limits of the rubber and radial cords. This could cause sudden tire failure.
Under-inflation will also cause poor handling, faster and/or irregular tire wear, and can
decrease fuel economy. Over-inflation, on the other hand, will reduce the tire’s contact
area with the road, which reduces traction, braking ability and handling. A tire that is
overinflated for the weight it is carrying is more prone to a harsh ride, uneven tire wear
and impact damage.
The level of air pressure required in each tire depends on the weight ofÂ the fully loaded vehicle. So the owner cannot correctly determine the right air pressureÂ unless he knows the vehicle’s actual weights. The maximum load capacity allowed for theÂ size tire and load rating and the minimum cold air inflation needed to carry that maximumÂ load are located on the tire’s sidewall. The lower the air pressure, the lower the loadÂ that the tire can carry. (A complete load and inflation table for Michelin RV tires isÂ available at www.michelinrvtires.com or by contacting a local Michelin RV tireÂ dealer.)
RV owners need to know the correct air pressure per axle for the vehicle, and they
need to know when and how often to check the tires. Here are a few recommendations:
- Check at least once a month and before any major trips.
2. On long trips, check everyÂ morning before driving.
3. Check before and after storage.
4. On short trips of a day orÂ less driving each way, check before you leave and before you return home.
Always try toÂ check tires when they are “cold” and have not been driven for more than one mile. TheÂ stated load capacity for a given cold inflation pressure is based on ambient outsideÂ temperatures. The pressure in a “hot” tire may be as much as 10 to 15 psi higher than aÂ cold tire pressure.
If the tires must be checked when they are warm, be sure to allow forÂ an increase in pressure, and make sure the pressure of the tires on both sides of the axleÂ are within a few psi of each other. Never let air out of a hot tire.
To make checking theÂ tire pressure easier and more accurate, Michelin recommends that the RV owner purchase aÂ quality truck tire air gauge with a dual-angled head. This allows the owner to check theÂ pressure of the inner and outer dual wheels. The easier it is to check the pressure, theÂ more often you’re likely to do it. Nothing should restrict the ability to check tireÂ pressure daily when driving.
Be sure to use pressure-sealing valve caps to prevent air fromÂ escaping the valve stem. If valve stem extension hoses are used, make sure they are goodÂ quality, solid stainless-steel braid reinforced and are securely anchored to the outerÂ wheel. The joints should be soaped immediately after initial installation to check for airÂ loss.
MAINTAINING MICHELIN RV TIRES
During any pretrip inspection, be sureÂ to check the tires for signs of aging, weathering and/or ozone cracking – these show up asÂ tiny cracks in the rubber surface on the sidewall of the tire. If the cracks are less thanÂ 1/32-inch deep, the tire is fine to run. Between 1/32 inch and 2/32 inch, the tire isÂ suspect and should be examined by a local Michelin RV tire dealer. If the cracks are anyÂ deeper than 2/32 inch, the tire should be replaced immediately.
Here are a few tips to helpÂ you proÂtect the tires from these common damage conditions:
1. Keep the tires properlyÂ inflated.
2. Keep the tires clean.
3. Avoid prolonged exposure to heat, cold or moisture.
4. Avoid prolonged exposure to ultraviolet rays.
5. Cover the tires when the vehicle is notÂ in use.
6. Do not park near electric generators or transformers.
7. Do not store theÂ motorhome in an area where welding is being done or in a garage that has mercury vaporÂ lamps.
Unless the motorhome is in full-time service, the coachÂ probably spends some time in long-term storage. But what is not commonly known is thatÂ rubber tires deteriorate when not being used. So, if you must store your RV, a cool, dry,Â sealed garage is the best bet. Also, some storage surfaces can cause tires to age faster.Â That’s why Michelin recommends placing a barrier (cardboard, plastic or plywood) betweenÂ the tire and the storage surface.
Here are some other steps motorhome owners can take toÂ help reduce the aging effects from long-term storage:
1. Thoroughly clean tires with soapÂ and water before placing into storage.
2. Cover tires to block direct sunlight andÂ ultraviolet rays.
3. Store out of a high ozone area.
Note: When a vehicle is stored, tiresÂ should be inflated to the inflation pressure indicated on the sidewall. Before removing theÂ vehicle from long-term storage, thoroughly inspect each tire – this includes sidewalls,Â tread area and air pressure. If the tires have lost air, be sure to inflate them to theÂ correct pressure before driving.
CLEANING AND DRESSING
Like the rest ofÂ the coach, it pays to keep the tires clean. Road oil will cause deterioration of theÂ rubber, and dirt buildup will hold the contaminants next to the tire. As with the cleaningÂ of any rubber product, proper cleaning methods must be used to obtain the maximum years ofÂ service from the tires.
A soft brush and normal mild soap that you would use to clean theÂ RV may be used. If a dressing product is used to protect the tires from aging, use extraÂ care and caution. Tire dressings that contain petroleum products, alcohol or silicones willÂ cause deterioration or cracking and accelerate the aging process. In many cases, it is notÂ the dressing itself that can be a problem, but rather the chemical reaction that theÂ product can have with the antioxidant in the tire. Heat can add to the negative reaction.Â When these same dressing products are used on a passenger car tire that is replaced everyÂ three to four years, it is rare to see a major problem. However, in most cases, RV tiresÂ may last much longer due to limited annual mileage, and the chemical reactions have muchÂ longer to take place.
GETTING A FLAT
Even the best drivers can drive overÂ a nail, and the best tires can pick up that nail or screw and go flat. If you pick up anÂ object that causes a flat in your RV tire, repair must be made to the inside of the tire.Â To do this, the tire needs to be demounted and inspected on the inside of the casing forÂ any other damage that the object may have caused.
RV tiresÂ should be inspected thoroughly at least once a year, and any time the owner drives in roughÂ or rocky terrain or is having the RV serviced. This inspection should include bothÂ sidewalls, the tread area, the valves, the valve caps and any valve extensions. Inspect forÂ nails, cuts, bulges, aging or fatigue cracks, as well as for weathering or ozone cracking.
Also, check between dual tires for any objects lodged between them. See a local tire dealer
at once if anything unusual is observed.
On a regular basis, rub the palm of your handÂ across the face of the tread on your front tires to feel for any feathered wear from “toe”Â alignment problems, but be careful since severe wear can expose steel belt edges that areÂ very sharp. A toe misalignment problem can be caused by impact with a “chuck” hole in theÂ road. Bad toe wear can be hard to find visually, but can be felt very quickly with theÂ hand. This type of alignment problem can wear rubber off the tread of the tires in just aÂ few hundred miles.
LEVELING RVS ON RADIAL TIRES
When using blocks forÂ leveling, extreme caution must be taken to make sure the tires are fully supported. TheÂ weight on the tire should be evenly distributed on the block. And in the case of duals, itÂ should be evenly distributed on blocks for both tires. If not, the sidewall cables canÂ become fatigued and damaged, resulting in a sidewall rupture and a complete, sudden loss ofÂ air pressure. Note that in the correct method, the blocks are wider than the tread andÂ longer than the tire’s footprint. This provides maximum support to the tires and assuresÂ that the load is evenly distributed.
Choosing the right tires is only the beginning. TiresÂ play a big part in any motorhome use, so it is important to give them the proper attentionÂ they deserve. Understanding the importance of proper tire pressure, maintenance and storageÂ will help an RV stay up and running, while minimizing down time or lost enjoyment for theÂ RV owner.
Doug Jones is a customer engineering support manager at Michelin Americas