Most caravan owners inflate their tyres to whatever number is stamped on the sidewall and call it done. That number is the maximum pressure for the maximum load that tyre can carry. Unless your van is loaded to its absolute ceiling on every single wheel, you are almost certainly running the wrong pressure.
Over-inflation on a lightly loaded tyre reduces the contact patch, concentrates wear down the centre of the tread, and makes the ride harsh and bouncy. Under-inflation on a heavily loaded tyre generates heat, accelerates sidewall fatigue, and is the leading cause of caravan tyre blowouts in Australia. Getting the pressure right means matching it to your actual load — and that requires a bit of maths most people skip.
Why the Sidewall Number Is Not Your Pressure
Every tyre has a load index and a maximum pressure moulded into the sidewall. A typical caravan tyre might read 235/75R15 105S, where 105 is the load index. That index corresponds to a maximum load of 925 kg at a specific pressure — usually 350 kPa (50 psi) for a light truck tyre or 240 kPa (35 psi) for a passenger tyre.
If your actual wheel load is only 650 kg, inflating to the maximum pressure means the tyre is working well above the curve it was designed for at that load. The correct pressure sits lower on the inflation curve — the relationship between load carried and pressure required for that specific tyre construction.
Tyre manufacturers publish load-inflation tables for every tyre model. These tables show the correct pressure for a given load in stepped increments. The problem is that most caravan owners never look them up, and even if they do, they need to know their actual per-wheel loads first.
Step 1: Know Your Actual Wheel Loads
You cannot calculate correct tyre pressure without knowing how much weight each wheel is carrying. This is not the same as your van’s total weight or even its axle weight — load distribution across left and right wheels varies depending on how you pack.
The most reliable way to get per-wheel weights is a corner weighing session at a public weighbridge. Some weighbridges offer individual wheel pads; others provide axle weights that you can split. Caravan clubs and tyre retailers occasionally run free weigh days — take advantage of them.
Weigh your rig loaded the way you actually travel. Full water tanks, gas bottles connected, fridge stocked, and gear packed where it normally sits. A weigh done with empty tanks and no gear gives you a number that is useless on the road.
Step 2: Find Your Tyre’s Load-Inflation Table
Once you know your per-wheel load, you need the manufacturer’s load-inflation data for your specific tyre. This is usually available as a PDF on the tyre brand’s website, or from your tyre retailer. The table lists loads in kilograms against pressures in kPa or psi.
Find the row that matches or exceeds your actual wheel load, then read across to the corresponding pressure. If your wheel load falls between two rows, round up to the next increment. Never round down — the tyre needs at least enough pressure to carry the load safely.
Add a margin for temperature variation and road conditions. Most industry guidance suggests 10–15 kPa above the table figure for a caravan running on Australian highways, where ambient temperatures can swing 20°C between dawn and midday.
Step 3: Check and Set Pressures Cold
Tyre pressures must be set when the tyres are cold — before you drive, not at a servo after 50 km on the highway. Driving heats the air inside the tyre and raises the pressure reading by 15–30 kPa, which masks under-inflation and makes over-inflation worse.
Check pressures with a quality digital gauge. Servo airline gauges are notoriously inaccurate and should not be relied on for safety-critical pressures. A good digital gauge costs $30–$60 and pays for itself the first time it catches an issue.
If you tow with a dual-axle caravan, check all four tyres individually. Uneven pressures across a tandem axle cause the higher-pressure tyre to carry more of the load, which accelerates wear on that tyre and under-loads the other. Both tyres on the same axle should be within 5 kPa of each other.
Common Mistakes
Using the tow vehicle’s placard pressure for the caravan. Your car’s door jamb sticker shows pressures for the car’s tyres at the car’s weight. Your caravan has completely different tyres, a different load, and different requirements.
Setting all tyres to the same pressure. If your van has a heavier offside (common when the fridge, battery, and water tank are on one side), the offside tyres need slightly more pressure than the nearside. Per-wheel weighing reveals this imbalance.
Ignoring temperature changes. If you set pressures in Newcastle at 15°C and drive to outback Queensland at 42°C, the pressure rise from temperature alone can be significant. Check pressures each morning before driving.
Never checking at all. Caravan tyres lose 1–2 kPa per month just from natural permeation. A van sitting in storage for six months can be 10+ kPa below its set pressure before you even hook it up.
A Faster Way to Get It Right
Ready2Tow automates this entire process. Scan your tyre sidewall with your phone camera and the app reads the size code, load index, and maximum pressure automatically. Enter your payload across four zones that match your rig layout, and the app calculates the correct per-wheel pressure using real load-inflation data — not a rough estimate.
Colour-coded gauges show whether each tyre is safe (green), needs attention (amber), or is critically wrong (red). You get a clear verdict before you leave the driveway, not a nasty surprise 300 km down the highway. The full feature breakdown covers everything the app does, and the Free tier gives you a pass/fail safety check at no cost.
