One of the most important things to get right when setting up a caravan is the tyre pressure.
If the caravan tyre pressure is too high, you’ll be in for a bumpy ride, which can increase the chance of trailer sway and blow-outs. If the caravan tyre pressure is too low, you’ll experience an unstable ride, plus the extra pressure on the sidewalls can cause them to bulge or delaminate.
Use the Caravan Tyre Pressure Calculator to quickly find the correct inflation figure for your set-up. Plus, step-by-step instructions on how to find and read all of the relevant tyre information.
Note: This advice is to be used as a guide only. If you’re not 100% sure how to correctly work out your caravan tyre pressure, always seek advice from a tyre professional.
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Caravan Tyre Pressure Calculator
To use this Caravan Tyre Pressure Calculator, you’ll need access to four different measurements:
- Your Max Tyre Pressure (cold)
- Your Max Tyre Load Rating (in kg)
- Your Caravan’s GTM (Gross Trailer Mass)
- Number of wheels on your caravan (2 for a single axle, 4 for a dual axle)
Full instructions on where to find all of your caravan tyre information can be found below the calculator.
These tyre pressure calculations are for on-road use only. For off-road caravanning (including extended corrugations), always drop the tyre pressure by 40 – 50%.
Finding Caravan Tyre Pressure Information
Always use Cold Inflation Pressure when calculating caravan tyre pressure, as tyres will increase in psi as they warm up while driving.
Finding TYRE PRESSURE on the Caravan Compliance Plate
If your caravan still has the standard tyres that were fitted by the manufacturer, you can access your tyre pressure information on the caravan compliance plate.
You should see:
- Tyre Pressure (cold)
- Tyre Pressure (cold) Max Loading
Quite often these figures are listed in kPa, so you will need to convert them to psi using a simple kPa to psi converter.
For example, using the compliance plate above, 345 kPa converts to 50 psi.
Finding TYRE PRESSURE & MAX LOAD RATING on the Tyre Sidewall
If you bought your caravan second-hand or you know that the caravan tyres have been changed, it’s best to use the tyre pressure information on the tyre sidewall, rather than the caravan compliance plate.
You will find:
- Max Inflation Pressure (this is the max cold tyre pressure)
- Max Load (this is the max amount of weight that can be loaded onto each tyre)
If your tyre has “Max Load Single” and “Max Load Dual” printed onto the sidewall, always use the Max Load Single.
Finding TYRE LOAD INDEX on the Tyre Sidewall
If your tyre doesn’t have the Max Load Rating (kg) stamped onto it, then you’ll need to decode this figure from the other tyre information printed on the sidewall.
Using the example pictured above, let’s break down what the tyre information means.
| 235 / 50 R 19 99 V | (meanings) |
|---|---|
| 235 | = Tread Width (mm) |
| 50 | = Aspect Ratio (e.g. tyre wall height is 50% of tread width) |
| R | = Construction (e.g. Radial) |
| 19 | = Rim Diameter (inches) |
| 99 | = Load Index → this is the figure you’ll need for the table below |
| V | = Speed Rating |
Caravan Tyre Load Rating (with table)
The Load Index is a number between 60 and 130, which correlates to the maximum weight allowed per tyre (from 250 kg to 1,900 kg).
Locate your Tyre Load Index (explained above) in the following table to find how much weight each of your tyres is rated to carry.
For example, if your Tyre Load Index is 99, then all of your tyres can carry up to 775 kg of weight each.
Calculating COMBINED Tyre Load Rating
It’s important to ensure that the tyre load rating of all your tyres combined is high enough to carry the weight of your fully-loaded caravan when hitched up to the tow vehicle (GTM).
To find that, you multiply the single tyre load rating by the number of wheels on the caravan (x 2 for a single axle, x 4 for a dual axle).
How to Calculate Combined Tyre Load Rating:
- Find the Tyre Load Rating (kg) on the sidewall of your tyre
- OR find the Tyre Load Index & use the table above to convert it into a kg figure
- Multiply your Tyre Load Rating x the number of wheels on the caravan
- Make sure your combined tyre load is enough to carry your fully-loaded caravan (GTM)
| Example: • Tyre Load Index: 99 • Each wheel can carry: 775 kg ➤ SINGLE AXLE caravan (775 kg x 2 wheels) = 1,550 kg Combined Load Rating ➤ DUAL AXLE caravan (775 kg x 4 wheels) = 3,100 kg Combine Load Rating Therefore, your caravan’s GTM cannot exceed 1,550 kg for a single axle or 3,100 kg for a dual axle. |
Calculating ACTUAL Load You’ll Be Putting on Each Tyre
To find the ACTUAL weight that your caravan will be putting on each tyre, take your caravan’s GTM and divide it by the number of caravan tyres.
| Example: • Caravan GTM: 2,800 kg • Number of caravan wheels: 4 (dual axle) 2,000 ➗ 4 = 700 kg So, the ACTUAL weight that each tyre will be carrying is 700 kg each. |
How to Calculate Caravan Tyre Pressure
Now that you’ve found all of your figures, here’s how to work out the exact tyre pressure for your caravan.
How to Calculate Caravan Tyre Pressure:
- STEP 1: Max Tyre Pressure (cold) ➗ Tyre Load Rating (kg) = “FIGURE A”
- STEP 2: “FIGURE A” x Actual Load on Each Tyre
→ the figure you get is the correct inflation pressure for each tyre on your caravan
| Example: • Max Tyre Pressure (printed on sidewall): 51 psi • Tyre Load Index (printed on sidewall): 99 • Tyre Load Rating (in kg → from table above): 775 kg • Actual Load on each tyre (GTM ➗ # wheels): 700 kg 51 ➗ 775 x 700 = 46.06 The correct inflation pressure for the caravan tyres is 46 psi |
Or, input your figures into the Caravan Tyre Pressure Calculator at the top of this post.
Check your Tyre Pressure Using the ‘PSI Rule’
The best way to physically check if you’ve got the correct tyre pressure in your caravan tyres is by using the ‘PSI Rule.’
Tyres will naturally heat up once you’re driving, so a good rule of thumb is to see a 4 psi increase in pressure for road tyres and a 6 psi increase in pressure for 4WD and light truck tyres.
Psi increase when tyres warm up:
- 4 psi – Road tyres
- 6 psi – 4WD & light truck tyres
How to check your tyres using the PSI Rule:
- Make sure your caravan tyres are cold (not driven for at least 2 hours)
- Inflate tyres to the correct pressure (as calculated above)
- Tow the caravan fully-loaded for 100 km (preferably on the highway)
- Measure ‘hot inflation pressure’ immediately
If your hot inflation pressure was 4 or 6 psi higher (depending on which tyres you’re running), then your cold tyre pressure is correct.
What if it’s more or less than the recommended increase of 4 or 6 psi?
If the tyre pressure…
- Increased MORE than 4 or 6 psi → Cold tyre pressure is too low, inflate the tyres a bit more
- Increased LESS than 4 or 6 psi → Cold tyre pressure is too high, deflate the tyres a bit
If you find that the tyre pressure is incorrect, you’ll need to let the tyres completely cool down before fiddling with them. That way you will be able to tweak the cold tyre pressure, then retest using the PSI Rule until you get it right.
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