Windsurf1 Posted June 14, 2019 Share Posted June 14, 2019 Hi, a very talked about subject but to find a definitive answer! The vehicle is a 2006 Starfire on a Boxer 2 chassis. Tyre pressures on collection, 55 F, 60 R. The tyres are 215x70RX15. Web searches suggest 73psi F/R. Plate on vehicle 79psi F/R. Any advice please as 79psi does sound high even if fully loaded? Thanks J C. Link to comment Share on other sites More sharing options...
aandy Posted June 14, 2019 Share Posted June 14, 2019 https://www.tyresafe.org/check-your-pressures/motorhomes/ Link to comment Share on other sites More sharing options...
Keithl Posted June 14, 2019 Share Posted June 14, 2019 John, To get meaningful tyre pressures you need your axle weights in your fully loaded condition. Failing this your best option is to set the pressures to match the MAX axle weight limits as stated on your VIN plate. If you want help please post either your actual axle weights or the max weights quoted on your VIN plate and the exact make and size of tyres including whether they are CP (Camping) or standard C (commercial) tyres. Keith. Link to comment Share on other sites More sharing options...
spirou Posted June 14, 2019 Share Posted June 14, 2019 Google continental technical hand book (or something like it) and you will find a pdf with all tyre sizes with appropriate pressures for various axle loads. But you will need to figure out what the loads actually are. Link to comment Share on other sites More sharing options...
Keithl Posted June 14, 2019 Share Posted June 14, 2019 spirou - 2019-06-14 7:05 PM Google continental technical hand book (or something like it) and you will find a pdf with all tyre sizes with appropriate pressures for various axle loads. But you will need to figure out what the loads actually are. https://blobs.continental-tires.com/www8/servlet/blob/85806/e0854f2c7866c64da551474b998ef8b3/download-technical-databook-data.pdf Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 15, 2019 Share Posted June 15, 2019 Windsurf1 - 2019-06-14 11:42 AM Hi, a very talked about subject but to find a definitive answer! The vehicle is a 2006 Starfire on a Boxer 2 chassis. Tyre pressures on collection, 55 F, 60 R. The tyres are 215x70RX15. Web searches suggest 73psi F/R. Plate on vehicle 79psi F/R. Any advice please as 79psi does sound high even if fully loaded? Thanks J C. The historical ‘norm’ for 215/70R15 size ‘CAMPING-CAR” tyres fitted to a motorhome has been 5.0bar (front axle) and 5.5bar (rear axle) - that’s 72psi(F) and 80psi®. For “CAMPING-CAR” tyres fitted to 16”-diameter wheels the historical norm has been 5.5bar/80psi for front and rear axles. However (as Keith has touched on above) if the tyres are NOT camping-car type (ie. not “CP”-marked nowadays - eg. 215/70 R15CP) and not designed to be operated at such high inflation pressures, the pressures would need to be adjusted accordingly. So the first thing to confirm is the specification (make and exact ‘name’) of the tyres fitted to your Starfire and then follow the advice above from other posters. (79psi front and rear will be unsuitable for 215/70 R15 tyres on a 2006 Autocruise Starfire. (image attached) Perhaps 73psi for camping-car tyres fitted to the rear axle if (say) a heavy scooter were being carried on a rear rack, but 73psi for the front tyres is likely to result in a harsh ride for the cab occupants. You may find that 55psi(F) and 60psi® is about right, but the only way to be sure is to obtain the motorhome’s axle-weights (via a weighbridge) in fully loaded ‘touring’ condition.) Link to comment Share on other sites More sharing options...
Windsurf1 Posted June 15, 2019 Author Share Posted June 15, 2019 Many thanks for the information you've posted. The tyres are Michilenins, Camping. The plate shows 79 psi F/R, but I guess that's if the vehicle was fully loaded. The Autocruise handbook states F44 psi, R 50 psi. Bit of a difference? True axle weight can only be determined on a weigh bridge. In conclusion I think F50 psi, R 60 psi would be a compromise? Thanks again for your help. J C. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 15, 2019 Share Posted June 15, 2019 As I said above, 5.5bar (79.7708psi) pressure for front and rear tyres would often be recommended for motorhomes fitted (for your age of vehicle) with 16”-diameter wheels and 215/75 R16CP camping-car tyres, but your Autocruise Starfire has 15” wheels like my 2015 Rapido that also has Michelin “Agilis Camping” 215/70 R15CP tyres. My Rapido carries a ‘sticker’ stating that 5.0bar (72.5189psi) pressure should be used for the front tyres and 5.5bar for the rear tyres, advising that those pressures are for the motorhome being ‘at full load’. I use 4.5bar (65psi) for the Rapido’s front tyres and 5.0bar for the rears. In principle, if the Autocruise handbook advises 44psi (F) and 50psi ®, that’s what an owner should be expected to use. To establish whether those pressures are suitable (ie. safe) for your motorhome, or optimal, you’d need to visit a weighbridge. If you think F60 and R60 may be OK without knowing the motorhome’s ‘touring’ axle-weights that’s your choice, but if you want confirmation you’ll need to weigh your Starfire. Link to comment Share on other sites More sharing options...
Billggski Posted June 15, 2019 Share Posted June 15, 2019 If above 65psi, make sure you have high pressure valves. Link to comment Share on other sites More sharing options...
Windsurf1 Posted June 16, 2019 Author Share Posted June 16, 2019 Good point Bill. Is there anyway of identifying if HP valves are fitted? Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 16, 2019 Share Posted June 16, 2019 Examples of metal high-pressure clamp-in tyre valves in this advert https://www.auto4.co.uk/valves-and-valve-hardware/clamp-in-valves Flexible ‘rubber’ high-pressure snap-in valves are also available, but the metal type is more commonly fitted to motorhomes. Link to comment Share on other sites More sharing options...
Billggski Posted June 16, 2019 Share Posted June 16, 2019 I found the snap in ones seated better on my alloy wheels. https://www.tyrebaydirect.com/product/e600r-high-pressure-snap-in-valve/ Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 18, 2019 Share Posted June 18, 2019 The tyre valve on your link is normally referred to as a TR600HP (or sometimes as a ‘Transit Valve’ presumably because Ford factory-fitted them to some Mk 6 Transits for a while). They were discussed here: https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Steel-valves-or-rubber-valves-for-new-tyres/48950/ Link to comment Share on other sites More sharing options...
aandy Posted June 18, 2019 Share Posted June 18, 2019 For what it's worth, I've set my tyre pressures by Tyresafe's calculator since I had them fitted last year. I weighed the van loaded with everything I usually carry, and with water and fuel tanks full, then rounded up each axle weight by around 50kg to allow for variations in loading. I've just measured the tread depths after 8,000 miles and they are even across each tyre, which suggests that the pressures are correct. Link to comment Share on other sites More sharing options...
BS20 Posted June 18, 2019 Share Posted June 18, 2019 I had my Starfire weighed on a council weighbridge, front axle, rear ,then total weight after buying 4 new Michelin “Agilis Camping” 215/70 R15CP tyres. Sent the MH model and weight detail to Michelin and they sent me the tyre pressure details. As each van weight is different I prefer not to state the pressure so you don't get the wrong advice. Link to comment Share on other sites More sharing options...
jumpstart Posted June 19, 2019 Share Posted June 19, 2019 Some air pumps at garages state they only go up to 60 psi. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 19, 2019 Share Posted June 19, 2019 BS20 - 2019-06-18 5:55 PM I had my Starfire weighed on a council weighbridge, front axle, rear ,then total weight after buying 4 new Michelin “Agilis Camping” 215/70 R15CP tyres. Sent the MH model and weight detail to Michelin and they sent me the tyre pressure details. As each van weight is different I prefer not to state the pressure so you don't get the wrong advice. Michelin’s standard policy regarding inflation pressures for vehicles fitted with “Agilis Camping” tyres is to advise that rear tyres should be inflated to 5.5bar (80psi) irrespective of the tyre-size, the number of rear axles, or weighbridge obtained rear-axle loadings. It seems to be pot luck whether Michelin will provide ‘pressure-to-load’ recommendations for front tyres if these are “Agilis Camping”, or just advise a simple one-pressure-fits-all datum (eg. 5.0bar or 5.5bar) It might be useful to know how Michelin responded to your enquiry, even if you prefer not to quote the pressures. Link to comment Share on other sites More sharing options...
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