millera1 Posted June 17, 2018 Share Posted June 17, 2018 Hope somebody can help me. I have a 2009 tracker eks high top and am looking for tyre pressure advice. All the stuff I have read seems very confusing. References speed ratings and load index but nothing as simple as a chart showing me psi. Tyres are marked as "215/70R15 CP109R 69psi " I have found something on the autotrail Web site which gives numbers in bar and converting these to psi I get 72/front and 79/rear. Both seem very high. I am going on a long trip to south of France. Not towing but loaded up a bit. 2 adults. I would normally just put 65 front and 69 rear but thought I should check it properly for once. Tyres currently have 56 front and 65 rear. Is this OK?? All very confusing. Please advise. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 17, 2018 Share Posted June 17, 2018 Your Tracker’s tyres are almost certainly Continental’s “VancoCamper” pattern. These are designed to cope safely with an inflation-pressure of 5.5bar (80psi) and Fiat’s recommendation for ‘recreational vehicles’ fitted with 215/70R15 CP tyres will be to use pressures of 5.0bar/72.5psi (front tyres) and 5.5bar/80psi (rear tyres). Unless you are prepared to have your motorhome weighed in loaded ‘on holiday’ state to establish its actual axle loadings, I suggest you opt for 4.5bar/65psi (front tyres) and 5.0bar/72psi (rear tyres). That should be well on the safe side and near enough to the 65/69 pressures you would have chosen. If you think the vehicle’s ride is too harsh using those pressures, it would be wise to weigh the motorhome before reducing the pressures further. Link to comment Share on other sites More sharing options...
millera1 Posted June 17, 2018 Author Share Posted June 17, 2018 Many thanks. You were spot on on the tyre type. Much appreciated Link to comment Share on other sites More sharing options...
Willum Posted June 21, 2018 Share Posted June 21, 2018 Derek Uzzell - 2018-06-17 3:10 PM Your Tracker’s tyres are almost certainly Continental’s “VancoCamper” pattern. These are designed to cope safely with an inflation-pressure of 5.5bar (80psi) and Fiat’s recommendation for ‘recreational vehicles’ fitted with 215/70R15 CP tyres will be to use pressures of 5.0bar/72.5psi (front tyres) and 5.5bar/80psi (rear tyres)..................... Derek: Thanks for the post, I'd just come on to try and find the explanation of the '69' PSI rating on the same make of tyre but a 225/75/R16, load indexed at 116. The tyres quote all the load limits at the same 69 PSI pressure. Forgive my brain picking but do you know why they quote 69 PSI yet, as you say, everything else is quoting 5.5 bar,(80PSI, or 79.77 for the really picky) all round, manuals (Knaus in my case) and Fiat door 'B' pillar included? Will Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 22, 2018 Share Posted June 22, 2018 I assume you are referring to a Continental VancoCamper 225/75 R16CP 116 tyre. The Load Index of 116 indicates that the tyre’s maximum load-capacity is 1250kg. When this tyre is used on a vehicle with ’single-wheel’ axles (ie. the axle has one wheel on each end) the maximum axle-load will be 2 x 1250kg = 2500kg. Continental’s Tyres Handbook indicates that, when this tyre is fitted to a single-wheel FRONT axle, the appropriate tyre-pressure to support an axle-loading of 2500kg would be 4.75bar (69psi). However, when this tyre is fitted to a single-wheel REAR axle the appropriate tyre-pressure to support an axle-loading of 2500kg would be 5.5bar (80psi). This link shows tyre sidewall markings http://generaltire.custhelp.com/app/answers/detail/a_id/850/~/tire-sidewall-markings Numbers 11 and 13 relate to respectively "U.S. load rating for max. Load” and "U.S. limit for max. inflation pressure”. As I understand it, if a tyre manufacturer wishes to market their product in the USA, the tyre must carry those two data, but compliance with those data does not extend outside the USA. I’m pretty sure that the equivalent specification Michelin “Agilis Camping” tyre would show 80psi as being the appropriate pressure for its Load Index ’maximum’. Consequently, I can’t tell you why Continental would indicate a 69psi maximum when it’s clear that the tyre can be run at 80psi - you’d need to ask Continental. Link to comment Share on other sites More sharing options...
Willum Posted June 22, 2018 Share Posted June 22, 2018 Mant thanks, Derek. The Continental marking of 69 PSI is confusing but that said, the Michelin Agilis I've had quote a pressure of 75 PSI in the same instance. Either way, I didn't think Knaus would have got it that far wrong. Will Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 22, 2018 Share Posted June 22, 2018 If the Michelin tyre were an “Agilis Camping” with 225/75 R16CP specification I’d expect it to carry an 80psi pressure-marking.. If the Michelin tyre were an “Agilis Plus” 225/75 R16C (ie. a ‘commercial vehicle’ tyre) it wouldn’t surprise me if it carried a 75psi marking as Continental’s “Vanco 2” pattern (equivalent to Michelin’s “Agilis Plus”) in 225/75 R16C specification has a 5.25bar (76psi) maximum-pressure recommendation. Link to comment Share on other sites More sharing options...
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