Tyre Pressure Rating - Urgent opinions sought

[JohnM20]

Hi All
I've just had my caravan serviced by a mobile Approved Workshop and included were two new tyres.
The caravan specification says that the tyres should be inflated to 50psi for the max weight of 1350kg although I never have the caravan anywhere near fully loaded and have frequently run the tyres at 45psi (the lower figure in the caravan spec. details). BUT, and this was spotted by the workshop, the new tyres that have been fitted only have a maximum inflation of 44psi although their weight loading is OK for the weight of the caravan, (the old tyres as originally fitted by Abbey were rated at 50psi max.). The workshop is going to check with the tyre supplier about this anomoly as he has said "this might be OK being as they are on a caravan and there is possibly a wide tollerance".
Personally I'm not happy. I have a 2000 mile trip to France in 10 days time and the last thing I want is a blow out. Also, I am guessing that my caravan and possibly my car insurance will be invalid if I knowingly use tyres with a maximum inflation figure lower than that required. It may also be illegal for the same reason.
Is there a tyre expert out there that can give me any urgent advice please ?

 

[otherclive]

I had a similar issue once and quickly told the dealer to put the correct spec tyres onto the van. He did so. In my experience tyre pressures are similar for tyres with the same load index, so I would not expect such reduction. Check with the makers handbook, your side tally plate on the van and also contact the maker. At the end you can reject the tyres and get some of the right spec on the internet well within 10 days.

 

[plotter]

It might be worth giving E Tyres a call as I found them very helpful when changing the tyres on my Abbey a couple of months ago.

 

[ProfJohnL]

Hi All
I've just had my caravan serviced by a mobile Approved Workshop and included were two new tyres.
The caravan specification says that the tyres should be inflated to 50psi for the max weight of 1350kg although I never have the caravan anywhere near fully loaded and have frequently run the tyres at 45psi (the lower figure in the caravan spec. details). BUT, and this was spotted by the workshop, the new tyres that have been fitted only have a maximum inflation of 44psi although their weight loading is OK for the weight of the caravan, (the old tyres as originally fitted by Abbey were rated at 50psi max.). The workshop is going to check with the tyre supplier about this anomoly as he has said "this might be OK being as they are on a caravan and there is possibly a wide tollerance".
Personally I'm not happy. I have a 2000 mile trip to France in 10 days time and the last thing I want is a blow out. Also, I am guessing that my caravan and possibly my car insurance will be invalid if I knowingly use tyres with a maximum inflation figure lower than that required. It may also be illegal for the same reason.
Is there a tyre expert out there that can give me any urgent advice please ?

You have answered your own question. The tyres must conform or better the standard specified by the trailer manufacture. In this case the inflation pressure is inadequate, and yes the caravan may be deemed unsafe which calls into question your insurance cover. Tell your supplier you reject the tyres (regardsless of what the tyre supplier says) and that they muust change the tyres for ones of the correct specification for the caravan.

 

[waffler]

I am not a tyre expert but think there is some confusion here. Tyres have a range of constructions and a range of rubbers. So mud and snow tyres have softer compound and tread that digs in sideways. Low rolling resistance tyres have stiffer walls and hard compound. So when Abbey fitted your original tyres the tyre manufacturer specified a a running pressure which Abbey included in the handbook. Your mechanic has fitted new tyres which happen to have a lower pressure. They may have more steel bracing for example which allows a lower pressue. I think that as long as the load factor is right, and the maximum speed factor, then you probably have nothing to worry about.

 

[Damian]

The only factors which matter are load capacity of the new tyres, correct size of tyres and the MTPLM of the van.
Speed rating is somewhat immaterial as every tyre is made to work at speeds over 60 mph anyway.

Quote "The tyres must conform or better the standard specified by the trailer manufacture. In this case the inflation pressure is inadequate"

Without seeing the tyres the above quote is wrong as they may be at least as good as the originals, and the tyre pressures may well be right for the new tyres.

Just as an example, take a 165/80/R13 with a load index of 83 on a standard car tyre, the tyre pressure is 35psi.
a 165/80/R13 with a load index of 83 but a reinforced tyre, the pressure is 41psi
and a 165/80/R13 light commercial tyre which has the lowest load rating available of 94, the pressure is 65psi

So, without the actual details from the tyre it cannot be said on the forum that they are wrong.

 

[ProfJohnL]

Hello Damaian,

Perhaps I am wrong on this one, but as the caravan manufacture specifies the tyre, size and type inflation pressure, a tyre that cannot be taken to that pressure does not match the trailers type approval.

There is the danger that a new owner my follow the manufacturers specification and due to the lower pressure rating of the new tyre, they may over inflate them with attendant danger that might ensue.

 

[Damian]

As far as tyres go, it is Load index and Axle Load which determine safety of the tyre, not what a manufacturer may "think" is right.
As many people have found when trying to replace tyres, the original type fitted are no longer available and have to go for the nearest "same as" or a higher load spec to satisfy the safety limitations.

Type approval would not be compromised by fiting higher spec tyres, with possibly lower pressures, as long as they adhere to the Tyresafe Tables.

 

[Guest]

Agree with Damian, however, it would appear the originals with a maximum pressure of 50psi were 'reinforced' tyres and at a guess,195/70R14 95 and of Matador make? Matador quoted higher than 'standard' recognised maximum pressures. Replacements I would then expect to be of a different make and conforming more to recognised standards.
However in either case and regardless of stated maximum pressures, the 'standard pressure' is what pressure charts go up to, there is then no load quoted for 50psi! In the case of the above size, it's 1380kg at 42psi.
If I'm correct, it might also then be worth pointing out, these tyres are very difficult to obtain and expensive if found, above all, at their maximum they are not really suitable. Swift, if asked today, recommend changing to 185R13 102 commercial tyres, as it happens, 50psi is correct for these and 1350kg, your prefered 44psi being quoted for 1245kg

You then need to enquire fully as to exactly what tyres are fitted and which they replaced.
...........................
Tyre pressure BTW is purely a result of compressing the required volume of air into the available space inside the tyre. The volume is a fixed for any given load, the various pressures for the same load occur because tyres of different size and or construction vary in internal volume.
The actual construction only varies the tyres volume, external dimensions remaining the same for any given size of tyre, it has no effect on pressure due to being stiffer or softer.

 

[JohnM20]

Thanks to everyone who has taken an interest in this problem.
Below are some more facts:
Caravan - Abbey Vogue 460 manufactured 2007, MTPLM 1350kg. Tyre pressure shown on caravan plate / spec details 50psi
Original tyres fitted by Abbey: Elite 2 Extra Load Radial, 195/70R14 96S MP42 max. load 710kg max pressure 50psi, manufactured March 2007.
New tyres fitted: Federal Super Steel 731 195/70R14 XL 95H M&S max load 690kg max pressure 44psi, manufactured November 2011.

Talking to a tyre specialist yesterday he says he has never seen a tyre with a maximum pressure rating as low as 44psi. He stated that both the above tyres are considered to be 'budget' tyres. The new tyres cost me £60.00 each, fitted.

 

[otherclive]

If your tyre specialist had heard of Trailermaxx he would see that at the size quoted their max pressure is 42psi. Your replacement tyres don't give you the recommended 10% over MTPLM. I had such a problem with that size tyre when uprated my payload to MTPLM of 1400 kg and the Traliermaxx only gave 1420 kg so I then went to GT Kargomax ST 6000 which ran at 50psi based on GTs advice and latterly I have changed to Firestone Vanhawks at 185/75/14C which have virtually identical rolling radius to the originals and are easier to obtain in Europe.

 

[Gafferbill]

He stated that both the above tyres are considered to be 'budget' tyres. The new tyres cost me £60.00 each, fitted.

This for me this is the cause of your dilemma...... far better to pay around £85.00 each for a quality tyre with a C rating for commercial van tyre (as otherclive suggests).
These are far better tyres to fit as replacements on a single axle caravan.

 

[JohnM20]

Gafferbill says it is because of the price that I paid that I got unsuitable tyres. This may be so but it is probably best part of 10 years since I previously had to buy caravan tyres so I had no recent experience of caravan tyre costs.
Perhaps I should point out that I left it to an Approved Workshop to source and get the tyres fitted for me. I was quoted a price for what I assumed would be perfectly suitable tyres. An Approved Workshop should be in a position to order suitable tyres but, in fairness to them, it was them who spotted that the tyres only had a 44psi rating.

 

[Damian]

Unfortunately the Approved Workshop has had the wrong tyres fitted.
They have had a lower load rated tyre which has a minimal load allowance over the MTPLM.

As they were responsible, they should correct the situation at no cost to you, and maybe they will think more when getting tyres for customers.
It is no good them "noticing" the tyre pressure AFTER fitting,,,,,they should have given.the specification required BEFORE fitting, and checked they were suitable before fitting.
Price of tyre is not really a major factor as such, it is the basics that matter, Load Index and MTPLM

 

[Guest]

I think there is far to much emphasis being put on the max pressure stamped on the tyre, albeit the load index dropped from 96 to 95, these tyres of any make are regarded as the same regardless of the maximum pressure marked.
I was taking a shot in the dark with my first answer, but the 'MP' on the original tyres confirms I was perfectly correct, that MP is from a Matador tyre.
The workshop then would have reasonably choosen 'like for like', so their supplier cocked up by not knowing there are two load index ratings for this size tyre, both though, under current advice, are now inadequate as they are being run at their maximum load, far from ideal and they should be at least 10% under their maximum load.
For the rest, it's as I said, or as mentioned by Clive, the 185/75R14 102, but only if your bothered about precisely matching the original tyres diameter, 52psi would be correct for these at 1350kg

 

[colin-yorkshire1]

hi all,
the original tyres fitted to my bailey were 165Rx13 load index 82 with a pressure of 33psi, IMO they were totally inadequate for the job and after the second trip out were changed for 165Rx13c with a load index of 94 run @ 42psi. ok so they are well over rated for the size and weight of the van but peace of mind and all that,
they are of course much stiffer than the originals so the retro fitting of shock absorbers was required to stop the top cupboards emptying on route but well worth the effort. better tyres don't have to be expensive either local retailer quoted £120 for the pair fitted and balanced to replace with firestones which I will do shortly as they are now 5years old.

 

[JohnM20]

Just to add a bit more to this saga, when I bought the caravan new in 2007 the plate on it showed MTPLM as 1350kg but it was some considerable time later that I noted that the Certificate for the caravan showed the MTPLM as 1295kg. I checked the VIN on the certificate which was correct for the caravan. I spoke to Swift who said that they would look into the matter and get back to me. A few days later a new certificate arrived showing the MTPLM as 1350kg.
Now, on reading what others have said about the maximum load rating for a tyre having a 10% margin above the MTPLM then a 96 tyre at 710kg is still, strictly speaking, below that required for a 1295kg caravan. I calculate that it should be 712kg.
The big question, of course, is should the caravan be rated at 1350kg or 1295kg ?

 

[otherclive]

2kg on the rating allowing 10% over MTPLM is neither here nor there, but I believe you should consider MTPLM as given by the maker in the revised certificate that aligns with the van tally plate. If you go for the lower MTPLM you will be giving up useful payload.

 

[Guest]

The 'T' in MTPLM is the answer to your question, 'technical' or technically it can be loaded up to this weight.
(I'll go one further and say, the absolute maximum is on the axles 'safe working load' plate which may well say in your case say 1400kg?, at the end of the day and provided the tyres can carry 1400kg then you cannot be breaking any laws loaded to that, IMO).
So in all truth, it's the actual weight of the van that matters, not it's potential, your new 95 rated tyres are fully loaded at 1380kg and if you knock 10% off and treat that as a maximum, then 1242kg conforms with current advice and the tyres will more happily cope with loading the van too that.
However and to quote from Tyresafes pressure chart, (they rounding up or down to the closest pressure to the ideal 10%), the 95 rated tyre has a safer maximum for caravan use of 1265kg @38psi, the 96 tyre is 1301kg also at 38psi

 

[Gafferbill]

Gafferbill says it is because of the price that I paid that I got unsuitable tyres. This may be so but it is probably best part of 10 years since I previously had to buy caravan tyres so I had no recent experience of caravan tyre costs.

......I am sorry I failed to get my point across and I understand that the tyre fitter may have been at fault.
He should of definitely given you a choice of tyres that you could of fitted and this would of demonstrated to you the range available both as to price and specification..
I personally go for a higher spec tyre for my caravan regarding 'load index' and experience has taught me that these cost more than fitting a budget tyre.

Personally I'm not happy. I have a 2000 mile trip to France in 10 days time and the last thing I want is a blow out.

........ I entirely agree with these sentiments.
Bare in mind that for this trip alone, you will pay well over £400.00 for fuel for your Mondeo.

Tyres are relatively cheap in the scheme of things nowadays

 

[Lutz]

There is no real need to allow another 10% margin over the MTPLM as the tyres already include an adequate margin of safety over the load rating shown on the sidewall.

 

[DeliDave_]

Agreeing with Gafferbill,I need some tyres as mine aree 5 years old and we are off to france in a couple of weeks.Which make would you recomend for a Bailey Indiana S6

 

[otherclive]

I have fitted Firestone Vanhawk a commercial van tyre. Firestone are a Bridgestone subsidiary and when searching the Bridgestone website for tyres there was a link to Firestone and a comment that said (sort of)...

if you wanted tougher knock resistant tyres for harsher use ie white vanman on potholed streets and kerbing then look at Vanhawks. Not that I abuse tyres but given a tougher tyre over one more suited to high speed van use I opted for the Vanhawks. When I was in eastern Turkey last year I noticed many vans were fitted with them as they are made in Bridgestones factory in Turkey. If they can withstand the roads out there where you can be driving on hardcore for up to 10 miles at a time where the new roads are being built they should stand the rigours of caravanning.

 

[Gafferbill]

....... I went for Hankook RA08 commercial van tyres for my caravan but I had to order them and wait a couple of weeks.
They satisfy the higher load safety margins now recommended for caravans.......... http://goo.gl/CohVq