Imagine tyre checking 12 tyres towing a tandem off road caravan? With different road conditions and huge swings in ambient temperature, tyre pressure monitoring is important for safety and economy. A major problem faced by travellers towing off road caravans is maintaining proper tyre inflation: Although each vehicle sold has a placard that identifies the tire size(s) and the inflation pressures recommended, they dont show the best pressure when towing a caravan. In addition, the maximum load and inflation information is stamped on the sidewall of every tire, usually in the bead area just above the rim. However, under-inflation contributes to:
- Rapid and uneven tread wear,
- A loss in fuel economy,
- Poor vehicle handling
- Excessive heat buildup which may lead to tire failure.
There are 2 major causes of poor inflation:
- A small puncture from an imbedded nail or fencing wire can cause a tire to be significantly underinflated.
- Air permeates through tires slowly, so that they typically lose about 2 psi per month in warm climates, and even more in hot climates.
It is recommended that tire pressures be checked at least monthly and before long trips or when additional passengers and luggage are carried. Tire pressures should be checked regularly as radial passenger tires can be underinflated by 12 psi or more and still look normal.
Pressures should be checked when the tires are cold, i.e., when the vehicle has not been driven for several hours, and using an accurate gauge.
Every 5°C increase in ambient temperature above 20°C results in about a 5% change or approx. one psi increase in tire inflation pressure.
Over-inflation can occur when your tyres “heat up” after you drive off. Assuming the ambient temperature remains more or less the same, the tyre pressure will increase with the hot tyre. This will stabilize at a given pressure and you can measure the amount of the increase.
There is a rule of thumb for checking you have the correct tyre pressure for your vehicle and caravan is known as the “4 psi rule”.
Firstly you need to inflate all tyres to a starting pressure of either the one recommended by the manufacturer for a “cold tyre” or to the maximum pressure less 10%.
Then tow your off-road caravan for say a distance of 100 klm on bitumen.
Upon stopping, immediately recheck your tyre pressure while the tyre is still warm.
If your tyre pressure reading is greater than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then the tyres are getting too hot and your starting tyre pressure was too low. Under inflated tyres wear unevenly and lead to increased fuel consumption. They can also impair the handling of the vehicle in the areas of braking and handling.
If the tyre pressure reading is less than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then your starting tyre pressure was too high. You will need to run the test again (once the tyre has completely cooled) with less pressure until you find the right balance.
However, if you want to check this more accurately, and develop your own chart, you need both pressure and temperature readings of each tyre. You make your own chart by recording pressure and temperature and charting this. If a tyre falls outside of your line, there is probably a problem. TPMS (Tyre Pressure and Temperature Monitoring Systems) do this for you automatically. They have a band of temperature and pressure that you set and if this varies outside of the “alarm band” then you are alerted.
The topics in this eBook include:
- Why is tyre pressure and temperature so crucial?
- What is the link between Tyre Pressure and Temperature?
- Getting the starting pressure right
- Adjusting the pressure with the 4PSI or 6PSI rule
- Adjusting the pressure to the optimum
- Using a TPMS:
- Specifications of TPMS
- TPMS Kit from Kimberley
- Suggested Pressure and Speed for off-road conditions
- Conversion Table
- Is there an Optimum Tyre Size?
- Acceleration, Braking and Load Transfer
- Tyre Markings/ Tyre Size
- Tyre Ageing
This eBook stepsthrough the best way to set your tyre pressures.
It also leads into the benefit of using a TPMS (Tyre Pressure and Temperature Monitoring System).
The one shown will monitor up to 12 tyres with pressure and temperature alarms per tyre. It will give you better insight into tyre issues when travelling off road and recommendations that can save you repair time, money and ultimately protect your safety. Download it for free!