Useful Info - Tyres
The Importance of Air Pressure
The most important factor in maximizing the life of your tyres is maintaining proper inflation. Driving on any tyre that does not have the correct inflation pressure for the load of the vehicle is dangerous and may cause premature wear, tyre damage, and/or loss of control of the vehicle.
A tyre that is under inflated will build up excessive heat that may go beyond the prescribed limits of endurance of the rubber and the radial cords. This could result in sudden tyre failure. A tyre that is under inflated will also cause poor vehicle handling, rapid and/or irregular tyre wear, and a decrease in its fuel economy.
Overinflation will reduce the tyre's footprint or contact patch with the road, thus reducing the traction, braking capacity, and handling of the vehicle. A tyre that is over inflated for the load that it is carrying will also contribute to a harsh ride, uneven tyre wear, and will be susceptible to impact damage.
Maintaining correct tyre inflation pressure for each loaded wheel position on your vehicle is of the utmost importance and must be a part of regular vehicle maintenance.
What pressure should I have in My tyres?
The amount of air pressure you need to use is dependent on the weight of your fully loaded vehicle.
It is important to note that the cold inflation pressure for the tyre must never exceed the maximum inflation rating stamped on it.
When Should I Check my RV's Tyre Air Pressure?
Check your tyres when they are "cold" and have not been driven for more than one mile. The stated load capacity for a given cold inflation pressure is based on ambient outside temperature. If you must check your tyres when they are warm or hot, do allow for a slight increase in air pressure and make sure they are within a couple of pounds of each other on the same axle. Never let air out of a hot tyre.
It is recommended you purchase a quality truck tyre air gauge which has an angled dual head. This type of gauge allows you to check inflations on the inner dual wheel which has the valve stem pointing toward you, and on the outer wheel which has the valve stem pointing away from you. Nothing should restrict your ability to check a tyres air pressure daily when you are driving your RV. Pressure sealing valve caps should always be used to prevent air from escaping from the valve stem. If you use valve stem extension hoses, make sure they are good quality stainless steel braid reinforced and are securely anchored to the outer wheel. If your RV has wheel covers which must be removed to check the inflation, then consider removing them on a long trip, as the extra time and effort required may lead you to avoid checking your air pressure.
What if You Don't Check Your Air Pressure?
How to Determine Your RV's Correct Weight?
The GVWR (Gross Vehicle Weight Rating) and GAWR (Gross Axle Weight Rating) stickers on your motorhome (normally located on the support pillar next to the driver's seat) will show you the chassis manufacturer's and/or the motorhome manufacturer's total vehicle maximum weight ratings and per axle weight rating.
The GVWR is the maximum total weight for which the vehicle is rated - including passengers, fluids, and cargo. The GAWR is the maximum for which a single axle is designed. These per axle and total maximum weight ratings could be limited by the tyres, wheels, axle and axle bearings, springs, the vehicle frame, or other components of the vehicle.
The GAWR sticker is only a guide in knowing your maximum loaded axle weights and subsequently your correct tyre inflation pressure. Every motorhome, even of the same make and model, will vary in actual loaded axle weights, because of different options and personal loads.
While your actual, loaded axle weight should be below
the GAWR, you must weigh your motorhome in a loaded
condition to know its actual weight. Weigh the front
axle, the total unit, and then the rear axle. It is
possible for a vehicle to be within the GVWR yet overloaded
on an axle. It is even possible for one wheel position
to be overloaded, even though the GAWR has not been
You will need to find a public weighbridge in your local area. There will be a nominal fee to pay to weigh your vehicle, which is money well spent, following which you will be issued with a weigh ticket. This will indicate the weights of the front axle, gross vehicle weight and the rear axle.
How to Weigh Your RV?
There are various types of weighbridge available.
Common Tyre Damage and Tyre Wear
No tyre, regardless of its quality, is indestructible. Certain conditions of use and abuse can stress a tyre beyond reasonable operating limits, causing it to come out of service even when considerable tread remains. Such conditions are clearly indicated by the damage they leave on the tyre itself. Below are listed common types of damage and the signs they leave behind. Please understand that this list is by no means exhaustive and is intended only as a general guide.
In this last case, the fabric casing cords of the tyre actually stretch and expand, causing the tyre to touch or kiss, under load at the contact patch.
In extreme cases, the sidewall of the tyre is destroyed, from the excessive heat it endured, due to the weight of the vehicle pressing on the tyre casing without the cushioning effect of the correct air pressure, and due to the crushing/cutting action of the wheel as it rolls on the under inflated sidewall. According to guidelines put out by the Rubber Manufacturers Association, any tyre that has been run at less than 80% of recommended air pressure for the load it is carrying should be inspected for possible damage.
When one tyre in a dual configuration comes out of service due to under inflation/run flat damage, the other tyre in the dual configuration should be inspected immediately. If the unserviceable tyre was under inflated, that means the serviceable tyre was carrying more and more of the load for that wheel position. Consequently, it too may have suffered some casing damage.
As with the cleaning of any rubber product, proper care and methods in cleaning must be used to obtain the maximum service years out of your tyres. A soft brush and the normal mild soap that you would use to clean your RV may be used. If you use a dressing product to "protect" your tyres from ageing, use extra care and caution. tyre dressings that contain petroleum products or alcohol may cause deterioration or cracking.
In many cases, it is not the dressing itself that can be a problem, but more the chemical reaction that the product can have with the antioxidant compound in the tyre. Heat can add to the negative reaction. When these same dressing products are used on a passenger car tyre that is replaced every three to four years, it is rare to see a major problem. However, in most cases, RV tyres may last much longer due to limited annual mileage, and the chemical reactions have much longer to take effect.
Just like your fan belt and radiator hoses, the rubber in your tyres ages as well. In cooler, clean air locations, the expected tyre life will be longer than in high temperature, high ozone areas. Of course, as a tyre ages, you should inspect it more frequently.
This inspection should include both, the outside and inside sidewalls, the tread area, and the valves, caps, and any valve extensions. Inspect for nails, cuts, bulges, ageing, or fatigue cracks and weathering or ozone cracking. Also, check between the duals for objects lodged between them.
During the yearly or pre-trip inspection the tyres should be inspected for signs of aging, and/or ozone cracking. Look for tiny cracks in the rubber surface on the sidewall of the tyres. Most often the cracks are 360 degrees around the tyre.
If the cracks are less than 1/32" deep, the tyres are O.K. to run. Between 1/32" and 2/32", the tyre is suspect and should be examined by your tyre dealer. If the cracks are over 2/32", the tyre should be replaced immediately.
To protect your tyres from these common damage conditions:
On a regular basis, rub the palm of your hand across the face of the tread on your front tyres to feel for any feathered wear from "toe" alignment problems. (Be careful since severe wear can expose steel belt edges that are very sharp). A "toe" misalignment problem can be caused by impact with a hole in the road. Bad "toe" wear can be hard to find visually, but can be felt very quickly with the hand. This type of alignment problem can wear rubber off the tread of your tyres in just a few hundred miles.
Long-Term Storage/Selecting Replacement Tyres
Your RV is designed for recreation, not long-term storage. However, unless you are a "full timer", you have no other choice. Rubber tyres age faster when not being used. A cool, dry, sealed garage is your best bet for storage. However, many RVs are stored outside in the elements. Some storage surfaces may cause tyres to age prematurely. For this reason, it is recommended that you place a barrier (i.e. card board, plastic, or plywood) between the tyre and the storage floor/ground surface.
There are a few steps that you can take to reduce the ageing effects from long-term RV storage. Before putting your RV into storage or a non-use period, thoroughly clean your tyres. Then cover the tyres to block direct sunlight and ultraviolet rays. Store your RV out of a high ozone area. NOTE: When vehicle is stored, tyres should be inflated to maximum inflation pressure as indicated on the sidewall of the tyre.
Before removing your vehicle from long-term storage, thoroughly inspect each of its tyres. This means a close examination of each tyres tread area, and air pressure. If your pressure check indicates the tyres have lost air during storage, be sure to inflate them to the correct pressure for the current load before putting the unit into service.
The Use of Blocks to Level Motor Homes/RV's Equipped with Radial Tyres
Extreme caution must e taken to ensure that the tyres are fully supported when using blocks to level motor homes and/or RV's. The load on the tyres should evenly distributed on the block and in the case of duals, evenly distributed on blocks for both tyres. If not properly done, the steel cables in the sidewall of the tyres may be damaged and could lead to premature fatigue of the sidewall.
The 'Blocking' Methods
The correct and incorrect methods are shown above. Please note that blocks should be wider than the tread and longer than the tyres footprint. This provides maximum support to the tyres and assures that the load is evenly distributed throughout the tyre's footprint area.
Selecting Replacement Tyres for Your RV