Cy.G Posted November 30, 2016 Share Posted November 30, 2016 Hi , there's a max pressure stated on the side walls as well as other important information but is there a way of calculating how much pressure to set your tyres at with reference to the weight of load . 15'' Camping tyres 3700 maw. I do know the axel weights & the weight as it stands . I don't want to squirt in the max if it isn't needed making a harder ride , but I'm aware under inflation causes overheating .. Thank you . Link to comment Share on other sites More sharing options...
shaggy Posted December 1, 2016 Share Posted December 1, 2016 Hi CY.G , I emailed continental who were the manufactures of the tyres on my van, they sent me a chart of pressures for various weights. My tyres are 16" so no good forwarding to you if you have 15", but worth looking up the email address of your manufacturers and contacting them. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted December 1, 2016 Share Posted December 1, 2016 Cy.G I believe you own a Rapido 9048DF - a relatively compact A-Class design built (in your case) on a ‘light’ Fiat Ducato with Al-Ko chassis. It’s near certain that Fiat and Al-Ko will recommend tyre inflation pressures of 5.0bar and 5.5bar (73psi and 80psi approx.) for respectively the front and rear tyres, and - besides this recommendation appearing in the vehicle’s handbooks - there should be a ’sticker’ somewhere on the motorhome confirming this. I assume your Rapido has 215/70 R15CP tyres - either Michelin “Agilis Camping” or Continental “VancoCamper”. I haven’t got Michelin’s data for axle-load-to-tyre pressure, but the list below shows this information for a 215/70 R15CP VancoCamper. Each line shows a front-axle load (in kg), a rear-axle load (in kg) and the tyre pressure (bar/psi) necessary to support that load. So, a pressure of 3.0bar (44psi) is needed to support a front-axle load of 1425kg or a rear-axle-load of 1270kg. (F) ... ® 1425 1270 --- 3.0/44 1520 1350 --- 3.25/47 1615 1435 --- 3.5/51 1705 1516 --- 3.75/54 1795 1595 --- 4.0/58 1885 1675 --- 4.25/62 1975 1755 --- 4.5/65 2060 1830 --- 4.75/69 ........ 1910 --- 5.0/73 ........ 1985 --- 5.25/76 ........ 2060 --- 5.5/80 Michelin’s data for a 215/70 R15C Agilis Camping tyre will be approximately the same. A 215/70 R15CP ‘camping-car’ tyre has a Load Index of 109, indicating a maximum load per tyre of 1030kg. This explains why the axle-load figures (for an axle with a single wheel at each end) stop at 2060kg (2 x 1030kg). If you want to match inflation pressure to your motorhome’s axle-loads, you will need to establish those axle-loads by having the vehicle weighed in fully-loaded state. Link to comment Share on other sites More sharing options...
nimod Posted December 1, 2016 Share Posted December 1, 2016 http://www.tyresafe.org/wp-content/uploads/2015/12/motorhome-leaflet.pdf Link to comment Share on other sites More sharing options...
Derek Uzzell Posted December 1, 2016 Share Posted December 1, 2016 The tyresafe figures for a 215/70 R15CP tyre tally with Continental's, although Continental does not differentiate between a ‘live’ (ie. driven-wheel) rear axle or a ‘dead’ (non-driven) rear-axle. Nor does the recommendation of the ETRTO (European Tyre and Rim Technical Organisation) regarding the inflation pressure for “CP”-marked tyres on a motorhome’s rear axle (See Page 46 of this 2014 document) http://www.pneusnews.it/wp-content/uploads/sites/7/2013/08/ETRTO-RECOMMENDATIONS-EDITION-25-SEPTEMBRE-2014.pdf mention that the axle being ‘driven wheel’ (or not) matters. Link to comment Share on other sites More sharing options...
paulmold Posted December 1, 2016 Share Posted December 1, 2016 Michelin always give the same figure for rear axle regardless of weight - 85psi. Link to comment Share on other sites More sharing options...
Billggski Posted December 1, 2016 Share Posted December 1, 2016 I think that would be 80psi/ 5.5 bar. My rear axle was approaching the max, so I moved to 225 section Agilis Campers. Paradoxically, they were cheaper! Link to comment Share on other sites More sharing options...
Cy.G Posted December 1, 2016 Author Share Posted December 1, 2016 Thank you everyone for your feedback , most helpful . It is indeed a 9048df 3700kg 150bhp. I would much rather have a close idea than sheer guesswork . VOSA did a free weigh in for me locally and whilst we still need clothing water food & I better take the boss . Axel 1. 1710 Axel 2. 1610 Leaving 380kg so just about doable . Max psi 80 . But I'll run with that when I need to not at it's current weight & I do check my tyres . Thank you again . Cy Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted December 6, 2016 Share Posted December 6, 2016 Camper tyres the c in cp have a extra load reserve and up to 5.5 bar. Depending of your axle loads which you can read out if you have goldsmitt full air suspension i suggest to in flate your tyres in respect to axle loads. There are tables for It. Link to comment Share on other sites More sharing options...
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