Tyre Pressure Calculator | Meet the Trudgians

Tyre Pressure Calculator

Posted by on Mar 22, 2016 in Featured, Technical | 11 comments

Tyre Pressure Calculator

For many setting the correct tyre pressures for a caravan seems to be a dark art. The tyres clearly state a maximum pressure, but what should the pressure actually be ?

Some time ago I stumbled across a fantastic blog (Caravan Chronicles) post that shows how to correctly calculate the pressure. It requires some maths and understanding of what the markings mean on the tyre.

I have gathered the maths together and created an easy to use calculator for anyone wanting to set the correct pressures for their caravan.

So, here is what you will need to know before you start.

1. The Tyre
Simply write down the tyre code on the tyre. You will have something like this :
205 / 65 R 15 94 H

TyreLooking at our example tyre, we are interested in 2 sections of information from the tyre. To start we need to know what the Load Rating is on this tyre. In this example above it is 94. To fully understand the tyre code, have a look at this website.

The second piece of information is the maximum inflate pressure. This is written on the tyre wall away from the main tyre code. It will read something like “MAX PRESS 3.03BAR (44 PSI)” we will need the PSI value.

There is more information on the tyre, such as the date this particular tyre was manufactured, but this is not required for this calculator – it is a good idea to write it down for future reference however.

Some tyres have this Tyre code written on them :
185 R14C 102/100 Q

Again we are just interested in the load value, which in this case is 102/100 But which one is it ? This is quite simple. The 102 refers to a load rating if used on a twin axle. The 100 is the load rating if used on a single axle ‘van.

2. The Caravan
We need to know what the MTPLM is of your caravan. This is typically stamped into a plate somewhere near the door. Some newer caravans also include the tyre pressures, however many still do not have the tyre pressures included, this is where this calculator can help.

Also we need to know how many axels you have on the caravan. Typically you will have one axle (2 tyres), but possibly 2 axles (4 tyres). If you have no tyres, you are possibly standing in front of the garden shed!

So once you have all information, type it in below and see what your correct Tyre pressure should be.

Add all the details and click calculate, it will give you an indicative pressure that your caravans tyres should be set to.




If you like this calculator, you can add it on your own website too. Simply add this text to your page where you want the calculator to appear :

<div id="TyrePressureCalc"></div>

<script src="http://www.the-trudgians.com/js/TyrePressure.js"></script>

Many thanks.



  1. An impressive share! I’ve just forwarded this onto a friend who had
    been conducting a little research on this.
    And he in fact ordered me lunch simply because I discovered it for him…
    lol. So allow me to reword this…. Thanks for the meal!!
    But yeah, thanx for spending the time to discuss this matter here
    on your site.

    • Hi, thanks for the comment. No problems – glad to help, and i hope you enjoyed your meal 😉

      Take care


      • Hi dan,i too found this very usefull and imformative and also i have passed it on made all the more easier to do because you posted the url too thanks very much
        Regards Adrian

  2. Interesting situation,my Bailey handbook states 65psi but the plate on the van states 58psi.This is a Pegasus S2 Genoa single axle.So which is correct? How critical is it at these high pressures to get it spot on.

  3. Cheers for this.
    Lunar don’t seem to give an actual pressure, just the max PSI of the tyre, which I always thought was too high.
    They say 59 PSI, I ran at 50 PSI, using your calculator it’s 48 PSI. So not far out, but better to be exact.
    FYI, Lunar Quasar 544 2013.
    Keep up the good work.

  4. In the sample you give 100 for single axle ( 2 tyres on alle) and 102 for dual so 4 tires on axle. Its the other way around.

    • correct

  5. Awesome! Its genuinely amazing piece of writing, I have got much clear idea about from this post.

  6. excuse the ignorance but i’m using your calculator for a laden trailer which will work same as caravan. Question, what is the MTPLM in your calculator measured in? Is it Kilos as I could find any reference anywhere.

    • It is measured in kilos

  7. Hi Dan,
    I have watched a couple of your videos over the months, you obviously enjoy the world of caravanning and sharing some simple ways in keeping it simple. People like me, new to caravanning, need all the help we can muster.

    Congratulations on your Tyre pressure calculator, I too came across the calculation sheet presented by Caravan Chronicles. You have taken it a step further, once again, keeping it simple and User friendly. Tyre pressure and the understanding of, have been a real pain for me knowing if I’ve got it right.

    I have a Swift Challenger 584 and have always been told that I must keep the tyre pressure (single axle) at 61 psi. I’ve always felt that this to be too high however Swift and others recommend this pressure. Using the calculator on my present tyres (about to be changed from 185R14 with a 102 loading to 195R14, load rating of 104) my tyre pressure should be 57 psi. I guess there’s not that much difference. However the 195’s will come in at 54 psi which I’d feel more comfortable with.

    I’m running this van in Australia and often get strange looks when I tell them my Tyre pressure. The van has had an ATM upgrade from 1550 to 1600kg, axle loading of 1500kg.

    Would be keen to hear your thoughts on this.

    Regards, Les


  1. Caravan Tyre Pressure Guide - How to Calculate the Correct Inflation PSI - […] both Steve from CaravanChronicals and Dan at Meet the Trudgians have gone through the method of calculating caravan tyre…

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