Airstream Posted December 8, 2012 Share Posted December 8, 2012 Hi, Having had my rear axle uprated to 2100kgs my 112 (1120kgs) rated tyres are marginal to the max recommended "in use" loading ie 90% of max I have however found these Conti VancoFourSeason 225/70 R15C 112/110R 8PR Double branding 115N OWL These have a 115 (1215kgs) rating at the lower speed N or 87mph Has anyone out there used these tyres and how are they? Regards Ray web http://www.mytyres.co.uk/cgi-bin/rshop.pl?details=Ordern&cart_id=69497155.110.15546&kplz=&Cookie=froogle&typ=457445&dsco=110&r anzahl= Ray Link to comment Share on other sites More sharing options...
Keithl Posted December 8, 2012 Share Posted December 8, 2012 Hi Ray, I can't help specifically with the Four Seasons but our AutoTrail on a Merc Sprinter chassis is plated at 2240 kg on the rear axle as standard and was originally supplied by Merc with Vanco 8PR which I have just replaced with a full set of Vanco2 of the same size as yours. May I ask where does this 90% loading figure come from as I have never heard of it before and can find no reference of it on the Conti website. To me a load index is a load index and nothing less. BTW the new Vanco2 tyres seem a better ride than the old 8PR but then again there is a significant difference in age as the old tyres were 9 years old! HTH, Keith. Link to comment Share on other sites More sharing options...
Airstream Posted December 8, 2012 Author Share Posted December 8, 2012 Hi, Quote att. "To safeguard against overloading the tyres, the UK tyre industry strongly recommend that when choosing tyres, the maximum technically permitted mass (MTPLM) of the vehicle's axles should not exceed 90% of the tyre load capacity as indicated by the tyre’s load index. Regrettably this isn't always achieved; for example many motorhomes are fitted with Michelin or Conti Tyres with 109 load indices when their 1900Kg rear axle should have 110 rated tyres under the 90% rule" Other sources on the www Ray Link to comment Share on other sites More sharing options...
Airstream Posted December 8, 2012 Author Share Posted December 8, 2012 HiJust found the link re tyre safety and the 90% "rule" Ray http://www.motorcaravanning.com/tyresafe_mh_tyres_08.pdf Link to comment Share on other sites More sharing options...
Keithl Posted December 8, 2012 Share Posted December 8, 2012 Thanks ray, I hadn't noticed that quote in the Tyresafe leaflet before. I'm sure that we are OK as we certainly don't go over 87 mph at which they're rated to a much higher load as you say (2430 kg Axle load). Keith. Link to comment Share on other sites More sharing options...
Brian Kirby Posted December 9, 2012 Share Posted December 9, 2012 Airstream - 2012-12-08 4:31 PM Hi, Quote att. "To safeguard against overloading the tyres, the UK tyre industry strongly recommend that when choosing tyres, the maximum technically permitted mass (MTPLM) of the vehicle's axles should not exceed 90% of the tyre load capacity as indicated by the tyre’s load index. Regrettably this isn't always achieved; for example many motorhomes are fitted with Michelin or Conti Tyres with 109 load indices when their 1900Kg rear axle should have 110 rated tyres under the 90% rule" Other sources on the www Ray Not sure that is the same quote. What the Tyresafe document actually says is: "To safeguard against overloading the tyres, the UK tyre industry strongly recommend that when choosing tyres, the maximum technically permitted mass (MTPLM) of the VEHICLE should not exceed 90% of the tyre load capacity as indicated by the tyre’s load index." I agree your version is more logical, since the loads on each axle tend to vary quite widely on the same vehicle. What they seem to be saying is that for, for example, for an axle rated at 2,000kg, the tyres should be rated at 1,100kg each. Apply this test to the heaviest rated axle, then fit the same rated tyres to both axles. Link to comment Share on other sites More sharing options...
Robinhood Posted December 9, 2012 Share Posted December 9, 2012 TBH, I think you have to take the statement in the full context of the paragraph in which it appears, where it is preceded by: In the interests of safety it is prudent to avoid continuous operation at the tyre’s maximum load capacity. Surveys over the years show that the opportunity for unwittingly overloading a motorhome, or poorly distributing the weight are high. (followed by) To safeguard against overloading the tyres, the UK tyre industry strongly recommend that when choosing tyres, the maximum technically permitted mass (MTPLM) of the vehicle should not exceed 90% of the tyre load capacity as indicated by the tyre’s load index. If you do this, then it all rather reduces to a meaningless, bet-hedging mess, from which it is difficult to make much sense of what it is really trying to say. :-S Is the 90% recommendation meant to protect against "continuous operation at the tyre’s maximum load", or against "unwittingly overloading a motorhome, or poorly distributing the weight", or possibly both?. Whatever the target; as literally written, because of the general requirement to be "properly shod" for max axle load on the rear whilst the front max axle load is much lower, the advice is unlikely to create many problems for people. For example, my van is 3500kg MTPLM, with 1750/2250kg max axle loads. As a result, it is shod with 113 load index tyres (max 1150kg each to cope with the rear axle). Taken literally, the tyre load capacity for the vehicle is 4600kg, 90% of which is 4140kg (way above the MTPLM, which I don't exceed anyway). Now I do from time-to-time get close to the rear maximum, but if I don't exceed the load index, I expect the tyres to cope (indeed, if they are rated at 1150kg under normal, static, circumstances, I would expect them to have some leeway above this for transfer stresses). So, rather than read between the lines, I think it is only appropriate to interpret the paragraph as it is written, rather than re-interpet to suit one's thoughts. And, of course, without opening up the "overweight" debate again, it pays to have weighed your 'van under laden conditions, to be at least sure at that point that the (static) load index values are not being exceeded. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted December 10, 2012 Share Posted December 10, 2012 "To safeguard against overloading the tyres, the UK tyre industry strongly recommend that when choosing tyres, the maximum technically permitted mass (MTPLM) of the vehicle's axles should not exceed 90% of the tyre load capacity as indicated by the tyre’s load index. Regrettably this isn't always achieved; for example many motorhomes are fitted with Michelin or Conti Tyres with 109 load indices when their 1900Kg rear axle should have 110 rated tyres under the 90% rule" The above quotation in its entirety is taken from the "Weight" section on this webpage: http://www.motorcaravanning.com/vehicles/tyres.htm The first sentence "To safeguard..... tyre's load index." comes from the Tyresafe .pdf file, but the 2nd sentence "Regrettably this isn't ........the 90% rule." is clearly a personal opinion of the owner of the motorcaravanning.co.uk website. The logic of the 90% tyre 'rule' is based on two assumptions: 1: A motorhome is normally driven with a roughly constant load (ie. unlike a light commercial vehicle (LCV), a motorhome's overall and axle weights won't much alter during usage). 2. A motorhome's overall and/or axles weights when driven will always be close to their maximum permitted limits. While the first assumption is certainly true, the overall/axle weights of many motorhomes will remain well within their permitted maxima. If Airstream wishes to increase the 'safety margin' of his tyres, it's evident that Continental's VancoFourSeason pattern is not the only LCV tyre available in the 225/70 R15C size with a (reduced speed rating) 115 load index - for example, Avon AV9, Continental Vanco 2 and Dunlop SP LT800 (which is also an 'all season' pattern). Then there's Michelin's "Agilis Camping" that, although not 'double branded' to have a 115 load index, targets motorhomes being driven continuously with axle-loadings close to their maxima. Brian Kirby has hands-on experience of VancoFourSeason tyres and there are earlier forum references to that tyre in the threads retrieved via the link below: http://tinyurl.com/dy8p6v9 Link to comment Share on other sites More sharing options...
Robinhood Posted December 10, 2012 Share Posted December 10, 2012 ....the other factor that comes into play regarding the "safe" loading of the tyre is the fact that the load index (whilst defining the maximum load for the tyre) is quoted in conjunction with its speed index (which in the case of my tyre, is "R", i.e 106mph). From extrapolation of other tyre data, it seems reasonable to assume that running at lower speeds (I never get near 106mph ;-) ) will provide some safety "leeway", as long as the load index is not exceeded. As a result, for my "R" rated tyres, I'm pretty comforatble to run close the the index (i.e, above 90%, but below 100%). Link to comment Share on other sites More sharing options...
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