I was advised early on in my motorhome ownership that there’s 3 things I need to keep an eye on… 1 – The condition of the fresh water tank. 2 – My leisure battery. 3 – My tyres. (for most motorhomers there may be a 4th which is the wine stock!)
When we collected our current Frankia motorhome the ride was very stiff and you could feel every bump of the road. Alko chassis’s are known for a rough ride but after some research some people said they were able to relieve some of the hardness by adjusting the tyre pressure.
What is the correct tyre pressure?
Most motorhomes or campervans have a sticker inside the door stating the recommended tyre pressures but this is missing on ours.
Upon collection, all four tyres were inflated to just under 80psi (5.5bar). As an experiment I dropped the pressure down to 65psi (4.5bar) which did make the ride slightly softer. However I was concerned that the tyres were under inflated. I emailed the tyre manufacturers with the tyre type, model, type of vehicle, position of tyre, and the axle weight which was taken from when we had the van weighed. You could also find the axle weights on the VIN plate in the engine bay or door pilar but this is the maximum weights so unless you go to a weighbridge and obtain accurate fully loaded weights this is the next best figure. Both manufacturers came back to me within 48 hours with the recommended tyre pressures:
TOYO H09 215/70R15C on the rear with axle weight of 1561Kg: recommended to 50psi (3.4bar)
Michelin Agilis Camping on the front with axle weight of 1646kg: recommended to 55psi (3.8bar)
Both were even lower than I had experimented with.
I understand that the proper camper tyres such as the ones on our front have stiffer side walls and thus can affect ride quality.
If you need to convert PSI to Bar and other measurement values, see the chart below.
psi = pounds per square inch
kg/cm² = kilogram force per square centimetre
bar = err, well a bar (1 bar is about the same as normal atmospheric pressure at sea level)
kPa = kilopascal
Tyre pressures can change with temperature so if your tyres are hot then the pressure will read slightly higher.