Hi all its been a while since i posted here. But have now got rid of my old Swift Corvette 1989 in favour of my new to me Swift Challenger 530se 2003. Question is on my old van pressures were low like in the 33 psi region but my caravan book says that my Challenger needs 61psi in its 175 r14 tyres but max pressure is 65psi. So my question is this safe? as its close to the maximum pressure also the vans weight max load is 1429 and the tyres are only rated to 750/775kg so this is also close. As this is all new to me weight and size wise any advice would be appreciated many thanks.
The tyre pressure you need is very dependant on load so caravan manufacturers always quote the maximum figure. I have run lots of tyres at maximum pressure with no ill effects. This website is a useful guide to caravan tyres and pressures Tyresafe
David
Discounted Insurance Quotes for UKCampsite.co.uk visitors! Up to 12.5% off!
It would be an advantage if someone with the same caravan could offer advice but as a general guide the tyre sizes are the same as my caravan but have a look on the tyre wall to see if they are commercial tyres or not as they are designed to carry heavier loads so the pressure rating may be higher and also have a look on the tyre wall to see what the maximum pressure allowance is. The maximum weight of my caravan is 1300 kgs. and the handbook states the tyre size of 175 x 14 with air pressure of 50 psi. The tyre wall actually states maximum pressure 55 psi. so I know that the pressure is correct and within the safe limit.
If max pressure on tyrewall is 65psi then anything below that is safe. If load rating of both tyres add up to max weight of caravan then that is safe as well, the max load ratings of tyres are generally at well over 100mph so at caravan towing speed you have plenty of margin.
The tyres mentioned in fact must be 175x14C commercial van tyres with 98/99 load rating for 750/775kg load. So to get a higher load rating 185x14C tyres would need to be fitted which will fit if there is room under arches.
Provided tyres are in good condition with no sidewall cracking & less than about 6yrs old they are ok for caravan.
The 65 psi is the pressure at wich the maximum load of tyre may be carried up to maximum speed of tyre or if lower 160km/99m/h.
It is not the maximum pressure of the tyre , so you even are allowed to go over it a little, and its for measured cold, so inside tire temp is outside tire temp.
But to calculate the needed pressure , you can use my made spreadsheet . Can be found in next map on my One-drive ( former skydrive) that belongs to my hotmail adress with same username as hereCaravan trailer tyre pressure calculator
To use it first download it to your computer by RIGHT-CLICKING and then choose DOWNLOAD
Leftclicking or choosing open in Excell or WEB-App goes wrong. After download and eventual virus-check , open it in Excell Programm on your computer, but Open Office CALC can handle it too.
If you cant work it out give the details ( most already given) and I will produce a picture of it with your advice.
I add in my spreadsheet first a reserve tothe 1429 kg of 10% because of weigthdifferences L/R , pressure loss in time , little overloading etc..
Then I calculate it with a formula that gives a bit lower pressure then yours. But your logical calculation is not that bad, and easy for on the road. Made a picture of it, assuming the figures are right.
Added a what if weight is more of 60 kg wich can easyly happen and then still a weightdifference possible of 92 kg .
Little overweight and an weightdifference of 80 kg is not unusual for Caravans/travel-trailers.
Many thanks to all. I think im going to stick with the book then as you guys are all around that mark. Just seems high coming from my old van. Thanks for the help.