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How To Measure Your Caravan Tyre Pressure

How To Measure Caravan Tyre Pressure

Regularly checking and maintaining your tow vehicle and caravan's tyre pressure is a simple yet essential task that significantly contributes to both safety and efficiency on the road.

5 Reasons to regularly check your tyre pressure include:

1. Carvan Safety:

Incorrect tyre pressure can lead to poor vehicle control and delayed braking, especially during emergency manoeuvres. Underinflated tyres make it more likely to run off the rim, while overinflated tyres promote hydroplaning and wear the centre of the tyre much more rapidly, making them more susceptible to blowouts.

2. Tyre Wear:

Overinflated tyres tend to wear out the centre of the tread, while underinflated tyres wear out the edges more quickly. Maintaining the correct pressure extends the life of your tyres, saving you money on replacements.

3. Fuel Efficiency:

Underinflated tyres use more fuel. When tyres are underinflated, they have a larger contact patch with the road surface. An increased surface area creates more friction between the tyre and the road, which requires more energy to keep the same speed and therefore more fuel.

4 Load Carrying Capacity:

The air pressure inside a tyre determines its ability to support the weight placed upon it. When a tyre is properly inflated, it can effectively carry the load of the vehicle and its contents, including passengers, cargo, and any towing loads.

5. Environmental impact:

Applying the correct tyre pressure will extend the life of your tyres, resulting in less landfill. While in landfill, tyres can leach harmful chemicals and heavy metals into the soil and groundwater over time.

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When and How to check Tyre Pressure

You should check your caravan’s tyre pressure at least once a month, before each trip, and each morning you drive during a trip. To do this, we recommend investing in a TPMS (Tyre Pressure Monitoring System) to take with you on the road.

You will find a sticker located on the centre door pillar or fuel filler cap advising the correct tyre pressure. Unfortunately, this is not always the case with all caravans and RVs. Your Caravan Handbook usually quotes the tyre pressure for the original tyre size fitted and the caravan loaded to the MTPLM (Maximum Technical Permitted Laden Mass). As the load in your caravan can change or on older caravans, the tyre size might have changed, it is worth knowing how to calculate the correct pressure.

There are two methods available to find the correct tyre pressure:

Method 1 is based on the weight of your van and uses a formula to make the calculation and Method 2 is called the 4 PSI rule and does not require a formula.


Finding the correct tyre pressure

Method 1: 

To find the correct tyre pressures for your caravan, you can use a calculation method that provides the right pressure when the tyres are at their operational temperature, typically about an hour into your drive.

Here's how you can calculate it:

  • Determine the weight of your caravan.
  • Measure the size of the contact patch of the tyres in square inches.

The formula is as follows: (weight X 2.2 divided by 4 ) divided by contact patch of tyre in sq. inches = correct pressure.

Example Calculation:

Van weight say 2300 kg’s on a tandem axle ( 4 wheels ) or single axle ( 2 wheels ) with a tyre patch size of 35 square inches would look like this –

2300 x 2.2 = 5060 divided by four if a tandem van or two for a single axle equals 1265 divided by 35 equals 36.14 PSI, so the tyres would be set to this pressure after an hour's drive to get them up to road temperature.

Method 2:

The other way of achieving this result is to use what is called the 4 PSI rule which does not involve a formula.

The other way of achieving this result is to use what is called the 4 PSI rule which does not involve a formula. The 4 PSI rule for tyres is a guideline to help determine if your tyre pressure is correct based on the difference between cold and hot tyre pressures. Here’s how it works:

Step 1. Measure Cold Tyre Pressure

Check and record the tyre pressure when the tyres are cold, before driving. "Cold" means the car has been parked for several hours, ideally overnight, or has been driven less than one km.

Step 2. Drive the Car

Drive your car for approx. one hour at normal speed to warm up the tyres. This will increase the tyre pressure due to the heat generated from driving.

Step 3. Measure Hot Tyre Pressure

After driving, check and record the tyre pressure again, now that the tyres are warm.

Step 4. Compare the Pressures

Compare the hot tyre pressure to the cold tyre pressure.

a. If the hot tyre pressure is approximately 4 PSI higher than the cold tyre pressure, your tyre pressure is considered to be correctly set.
b. If the increase is over 4 PSI, your starting pressure may be too low.
c. If the increase is less than 4 PSI, your starting pressure may be too high.

In conclusion, ensuring your caravan's tyres are correctly pressured is crucial for safe and efficient travel. By following either of the two methods above, you can accurately measure and adjust your tyre pressure to maintain optimal performance.

For added peace of mind, consider investing in a Tyre Pressure Monitoring System (TPMS). Carac offers a wide range of TPMS options to suit your needs, these allow you keep a constant check on your tyre pressure while in motion.

If you have any questions or need further assistance, don’t hesitate to give Carac a call. Our team is always ready to help you with expert advice and support. Safe travels!

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