Ford Transit (mainly) tyre valves - possible danger.

[Brian Kirby]

If you have a Ford Transit year 2000 or later based motorhome please check the type, and condition, of the tyre valves as soon as possible.

Some, possibly most, of these Transits have been fitted with what are called High Pressure Snap-in valves.  These resemble normal car tyre valves, but have an exposed metal stem protruding from a rubber base, whereas the car type valve will be fully encased in rubber, i.e. from the wheel rim up to the valve cap.

It seems that these high pressure valves may be prone to failure of the bond between the rubber base element and the exposed metal stem, leading to air loss.  There is a further suggestion of some of the metal stems snapping.

Friends of mine who own a Transit based Autosleeper arrived at a channel port after an autoroute drive up from Bordeaux, and chanced to notice that one of their rear tyres looked low.  They found the pressure was around half what it should have been and, when the valve stem was flexed, could hear air escaping.  They got the valve replaced, thinking it an isolated case.  However, they then had a repeat experience some months later, which again they were lucky enough to spot before the tyre got too soft.  In either case the low inflation of the tyres could have caused a violent blow out, had they not noticed the problem before matters progressed too far.

Ford say they have no knowledge of this as a fault, but Derek Uzzell has spoken to a contact in the tyre trade who told him there is a recognised problem with such valves.  It just seems no one has told Ford!

Ford have now said that anyone experiencing this type of failure should report it to their nearest Ford dealer with a request to pass on the information to Ford via their technical hotline.

It is possible that the problem arises particularly in motorhomes, due to their smaller annual mileages, meaning the tyres, and thus the valves, remain on the wheels for much longer than would be normal with a commercial van.

Whatever may be the cause, the failure seems to result from perishing, or hardening, of the rubber element of these valves.  Therefore, if you have a post 2000 Transit based motorhome with tyres and valves that are more than three or so years old check what type of valve is fitted and, if they are of the type described above, give the metal stem a good wiggle and listen for escaping air.

If the valves do show signs of leakage, or if you have noticed a tendency for the tyres to loose pressure, get the valves changed pronto, but retain them, take them to a Ford dealer and ask him to report the failure/s to Ford's technical department via his technical hotline.

Y'all take care now.

[Derek Uzzell]

An update on Brian's warning... 1. A recent Auto-Sleeper Owners' Club newsletter (the July issue I believe) mentioned that an ASOC member with a 2005 Transit-based Ravenna had experienced failure of the tyre-valve on one of his motorhome's rear wheels while the vehicle was parked in his drive at home. The following month, while attending a Club rally in Italy, the valve on the other rear tyre failed. The Auto-Sleepers company has apparently reported the incident to Ford and asked for comments. 2. Last Saturday, towards the end of a fortnight's holiday in France, the high-pressure 'snap-in' tyre-valves failed on both rear wheels of my 2005 Transit-based Hobby. I don't know exactly when the first failure occurred but, having stopped at an aire de services, I noticed that the right rear tyre looked unusually bulgy at the bottom. Checking the pressure revealed 20psi rather than the usual 55psi. Thinking the tyre had punctured I started to change the wheel for the spare, when the left rear tyre spontaneously (and very loudly) began to lose air from the valve. Flexing the valve-stem of the right rear tyre (as Brian suggests in his posting) subsequently showed that the tyre had not punctured and the pressure-loss had also been due to valve failure. Both failed valves were capable of retaining 15-20psi but attempts to re-inflate the tyres beyond that point proved futile. Brian's precautionary advice makes good sense in principle. If a tyre-valve (whatever its type) shows visible signs of deterioration or damage, then it should be replaced. Similarly, if flexing a tyre-valve's stem causes air to be heard escaping, the valve clearly needs renewing. Obviously it's good policy to check tyre pressures on a regular basis. However, with first-hand experience as a victim of this specific phenomenon, my opinion is that there's actually no practical way to guard against it. Neither of the failed valves on my Hobby shows any external indication of deterioration/damage and the valves' rubber element remains fully flexible. The Hobby (and the Auto-Sleeper Ravenna I referred to earlier) are both under 3 years old and, while I don't know the mileage of the Ravenna, my Hobby has yet to reach 10,000. So valve-senility or heavy usage can be discounted. I'm careful about tyre pressures and had checked them just 3 days before the valve failures happened. In my case, flexing the valve-stem on the right-hand tyre confirmed that the valve had failed rather than the tyre had punctured, but I already knew there was a problem as the tyre looked flat. Vehicles fitted with these valves will invariably have relatively high tyre-pressures and the evidence (such as it is) is that valve failure results in the pressure falling radically and quickly. What I'm getting at is that, while valve-stem flexing may be useful to discriminate between a failed valve and a puncture, it's unlikely to provide any advance warning of the valve beginning to fail - basically, when these valves fail they fail big. By all means flex your high-pressure valve-stems, but if you hear air escaping then the tyre will almost certainly already be well down on pressure and, if you don't hear air escaping, that doesn't mean the tyre-valve won't fail immediately afterwards. On our return to the UK I visited the tyre-fitter who had previously told me that this type of tyre-valve had failed on local fleets of Ford Transit vehicles. He could offer no advice on how to detect potential valve failure and said that he'd replaced failed valves on FWD or RWD Transits and on the front or rear wheels. The 3 motorhome incidents appear to have involved 'partial' failure, with the valve remaining able to hold some pressure, but the tyre-fitter said he'd had instances where a valve's metal and rubber components had separated completely producing immediate and total air-loss. The only grain of comfort was that he said he hadn't encountered the valve-failure problem for some time. For anyone interested, there's a picture of a high-pressure 'snap-in' tyre valve on page 239 of May 2007 MMM. With a design pressure-range of up to 100psi, you'd think this valve should be capable of handling anything a Transit could throw at it, whether there's a motorcaravan, removal-van, or any other sort of body sat on top of the Ford chassis. While I've got no difficulty accepting that a tyre can fail if over- or under-inflated, or abused, I find it hard to understand why a valve of this type should fail unless it has been badly manufactured or there's a design or material fault. But, if that were the case, I'd expect there to have been a massive number of failures and there's no evidence this has happened. Hopefully something informative will come out of the liaison between Auto-Sleepers and Ford, because I haven't a clue about this. Besides following Brian's advice, I now strongly suggest that motorcaravanners owning vehicles fitted with these valves familiarise themselves with the terms and operation of their breakdown insurance and liberally festoon their motorhomes with Saint Christopher medallions!

[Guest JudgeMental]

Well Derrek, at least you where stationary! I tried to order my new van with steel valves but dealer was not aware of this problem. may visit a tyre place and see if they can be upgraded. it reminds me of an Oscar Wilde quote: To lose one parent may be regarded as a misfortune; to lose both looks like .......... :-D

[JohnP]

Brian There was a recall on Swift Kontiki 2003/4. They had a problem with valves on their alloy wheels. To Swifts credit they did contact the owners, with pictures identifying the valve types which may have been fitted and also identifying the faulty design. Some failures evidently lead to rapid loss of pressure.

[paul2]

I've had this problem on an Iveco Daily (at work) after changeing a rear damper refitted wheel let jack down as weight of van came back onto tyre the valve went. Paul

[Derek Uzzell]

Don Madge has pointed me towards the following link and I suggest all owners of motorhomes based on Year-2000-onwards Transits take a look. http://www.motorhomefacts.com/ftopict-20551-ford.html+transit

[handyman]

i have the valves with the exposed steel half way up. So what now? I'm inclinded not even to bother going to ford, as they are useless. My plan is to order correct HP valves, and get them fitted at national tyre.........any thought on this. A little concerned, as the back tyres are up at 5.5bar 78psi on the back.

[Derek Uzzell]

The valves that failed on my Transit-based Hobby are identical in appearance to the 'original' valve pictured on the MHF forum. The overall length (excluding valve cap) is 45mm, the distance from wheel-rim surface to end of brass stem is 35mm and the amount of exposed brass stem is 20mm. The characters "TR 600 HP" are moulded around the rubber part of the valve just below where the brass stem emerges from the rubber base. On the underside of the rubber base (invisible inside the wheel once the valve is fitted) are moulded the letters "F H A" and the word "GERMANY". If you can ascertain that your Transit-based motorhome is fitted with these valves, then I suggest you consider getting them changed. It's possible that forum members may be confused by the MHF statement "The Ford part number for the correct valve is: 4688245". This valve is likely to be the one employed on variants of the latest version of Transit. It's just a common-or-garden high-pressure snap-in valve intended for use when tyre inflation pressures exceed the ordinary snap-in valve's 65psi design-limit but do not exceed 100psi. What I'm saying is that any HP snap-in valve that will fit a Transit's wheel should be equally suitable. There's nothing 'Transit-specific' about the 4688245 valve and, should you need (or choose) to have a Transit HP valve changed, there's a very good chance that the tyre-fitting company will stock a different make of HP valve that may look somewhat different. Should this be so, there is no reason to assume such valves are in any way 'incorrect'. Having said that, if you can get your hands on the 4688245 valve, it makes sense to do so. With no useful data to draw on, the cause of these failures continues to be a mystery. The valves that have failed are high-pressure type and should easily be man enough for the job. Valves are manufactured in vast numbers and the process is totally automated. If there had been a quality control problem with the valves' rubber material or the way the valve were assembled, one might expect a general awareness of the fault and a lot of failures. But what we seem to have (in the UK at least) is a slight awareness of the problem within the UK tyre-fitting trade and a few isolated failures. The only pattern emerging suggests that the failures all involve the German-made valve. One thing's for sure - there's little point guessing. The best-known tyre-valve manufacturer is Schrader and I asked their UK organisation for advice about this. I was told that they distribute thousands of Schrader-made HP snap-in valves in this country each month and have had no problems reported with any of them. (I need to emphasise that the German-made valves that are failing are NOT Schrader products.) Schrader also markets a rigid clamp-in valve (the type used when SEVEL (Citroen/Fiat/Peugeot) motorhomes are factory-fitted with Michelin XC Camping tyres) that should fit the Transit wheel. handyman: Your Eura Mobil 622 SB is pretty similar in size/shape/weight to my 2005-model Hobby T-600 FC and is built on the same chassis. Given its age, it's also a reasonable guess that your motorhome has ordinary 'light commercial vehicle' tyres with a maximum design-pressure of no more than 70psi. (In my Hobby's case the tyres are Continental Vanco-8 215/75 R16C 113/111R.) My Hobby carries a Ford data-plate on a cab door-pillar advising tyre pressures of 3.0bar (43.5psi) for front tyres and 5.5bar (79.8psi) for rear tyres and it's quite likely yours does too. These recommendations are highly dubious ("wrong" is probably more accurate!) and may have arisen as a result of Michelin XC Camping tyres being fitted to early (pre-2005) chassis. I wrote to Ford(UK) about it in August 2005 and I think I've mentioned it before on this forum. If you check your Transit Owner's Guide I believe you'll find that 70psi is the maximum 'full axle load' inflation-pressure recommendation for any Transit model fitted with the 215/75 R16C tyre-size. With 5.5bar in your motorhome's rear tyres I would have thought the ride is pretty darned harsh on other than very smooth road surfaces. I suggest you get the vehicle weighed in fully loaded state and then seek advice from whatever manufacturer has produced your tyres. For what it's worth, I use 3.2bar (front tyres) and 3.8bar (rear tyres).

[handyman]

The ford sticker on the cab states these pressures, as does the separate euramobil user manual, and would assume the van is very close to the max weight (3.5T) when loaded up, which it always is. It has Michelin XC Camping tyres fitted

[Guest JudgeMental]

Derek, my 2007 Ford EuraMobil hightop. Has continental Vanco tyres, 215/75 rim code 5.5J. Ford sticker reads Front 50.8 psi Back 68.9 psi (3.5/4.75 bar) so this is the way I run them. Could not ID serial no.(eyes to poor) on valves but have attached picture. Are these the offending article?

[Derek Uzzell]

JudgeMental: No - your valve looks like the one referred to on the MHF website as the 'correct' one, which is what one might expect as your Eura Mobil is built on the latest model Transit. There are photos on the MHF posting of the two different designs of valve, but I think you may have to enter the MHF website from Square One to be able to view them.

[handyman]

hi derek, see with the extra info i have supplied, is it ok to have the rear tyres at that pressure then? To add , when i got the van i ran it for a few months without checking the tyre pressure. The rear pressure was at 34psi. By increasing the pressure, i didnt notice any change in the handling of the van

[JENIAN]

Thanks Brian and Derek, I own a A/S Duetto 2001 and had similar experiances with my van. Over a period of the 6 months I have owned the van I have had to renew all four valves at different times due to valve failure over 20psi. Unfortunately I did not retain the old valves. I will order the 5 new correct valves from Ford forthwith and make them aware of this potentally dangerous situation. Ian.

[philo]

Hi, all. This thread has prompted my first post. Not quite the same problem, but more than a little disconcerting! Before setting off in our shiny, two week old, pride and joy I fuelled up and checked the tyre pressures. As I located the inflator gun on the front wheel valve there was a very loud bang as the valve dissapeared, leaving the tyre, and myself, immediately and completely deflated. The valve was subsequently found intact inside the tyre casing. It seems the HP valves do not locate as firmly within the rim as normal valves - in this case it may not have fully located, allowing the valve to move enough to allow air to rapidly escape around the seat, dragging the valve into the casing. I dread to think what may have happened had this become dislodged, perhaps by hitting a rut or pothole while travelling at speed! As the vehicle is a new twin wheel transit, I assume the valves fitted are the current type. For what it's worth, the tyre fitter at my local Ford agent (Transit specialist) has a very low opinion of the HP valves.

[Derek Uzzell]

handyman: I'm mildly surprised that a 2006-model motorhome based on the FWD platform-cab Transit chassis would have XC Camping tyres as original equipment (OE). I thought that, by mid-2005, all motorcaravans using that chassis would have 'ordinary' tyres (like Michelin's Agilis 81 or Continental's Vanco-8) as OE, just like every other Transit rolling off the assembly line. It might be interesting to check the exact dates of manufacture of your Eura Mobil's chassis and tyres. You state that you "assume the van is very close to the max weight (3.5T) when loaded up", which indicates to me that you've not had the vehicle weighed in that state. Now, for all I know you may regularly transport gold bullion or depleted uranium in your Profila, or have a shed-load of hugely heavy accessories fitted: otherwise it's hard for me to understand why your motorhome should be so heavy. The 2006 Eura Mobil brochure quotes the Mass In Running Order (MIRO) of a Profila 622SB as 2900kg. This figure includes allowances for a driver, full diesel-fuel and fresh-water tanks and gas bottles, leaving a very respectable 600kg of payload available for passenger(s), luggage and accessories. The MIRO of my Hobby T-600 FC is quoted as 2971kg. My Hobby is 16cm longer than your Eura Mobil and 1cm taller, while your motorhome is 8cm wider. There are two significant differences inside - the Hobby has far more storage volume (lack of easily accessible internal storage was one of the reasons I crossed the 622SB off my shopping-list) and its100 litres fresh-water tank is beneath the bed rather than in the front dinette seat-box. Given that my Hobby's MIRO is 71kg more than your Eura Mobil's to begin with and the vehicle has more room inside for the inevitable junk motorcaravanners carry with them, it's difficult not to assume that the Hobby will weigh more overall when loaded up and (because there's 100kg of water perched just behind the Hobby's rear axle) that the rear-axle loading will be higher on the Hobby than on the Profila. Vehicle overall weight is largely irrelevant to tyre-pressure suitability: it's axle-loadings that matter most. When I weighed my Hobby in loaded state the overall weight was 3140kg, front-axle load was 1400kg and rear-axle load was1740kg. (As I'm sure you know, the respective maximum authorised weights for this chassis are 3500kg, 1665kg and 2250kg.) To give me some additional 'breathing space' load-wise I augmented the weigh-bridge axle-load readings to 1520kg (front) and 1800kg (Rear) and I then asked Continental what tyre-pressures would be appropriate. I was told 45psi and 53psi respectively and I choose to use 47psi and 55psi. I had also asked Continental to give me inflation-pressure recommendations for the chassis' 1665kg(F)/2250kg(R) maximum authorised axle-loadings and was told 47psi and 69psi respectively. As I said earlier, I have always suspected that the 3.0bar(43.5psi) and 5.5bar(79.8psi) pressure recommendations on the Ford door-pillar sticker result from when XC Camping tyres have been fitted to this chassis. Michelin's UK technical handbook supports this theory as (for a 215/75 R16C XC Camping tyre) 43.5psi would be appropriate to a 1665kg axle-load. The inflation pressure for an axle-load of 2250kg would be around 63psi (Michelin's handbook quotes 65psi for 2300kg). So where does the 79.8psi figure come from? There's little doubt that this figure derives from Michelin's unfortunate handbook footnote relating to XC Camping. This footnote says "For maximum load conditions when used on mainland Europe it is recommended that the rear tyres are inflated to a pressure of 80psi". Michelin are happy to say that XC Camping is specifically intended to provide a 'safety zone' to cope with axle-overload beyond the tyre's stated 2300kg maximum. (They say their surveys have shown overloading of motorcaravans is commonplace in Continental Europe, though I reckon the UK's no different!) What Michelin won't reveal is the tyre's genuine design-maximum axle-load. If they did, they say, motorcaravanners would just consider that figure as 'safe' and then overload beyond it. It's probably 2500kg - an educated guess based on the data provided for the same size 10-ply rated Agilis 101 pattern and it's noticeable that the Agilis 101 tyre requires 76psi to support its 2500kg axle-load maximum. So there you go. Your Profila's XC Camping tyres are designed to cope with a 5.5bar inflation pressure, but to justify using that pressure you'd really need to have your motorhome's rear axle continuously loaded beyond its authorised maximum weight limit. My own experience with the Hobby makes me doubt the likelihood of this. I stand by what I said in the final paragraph of my previous posting - get your motorhome weighed and then seek advice from Michelin. You'll probably find that your motorhome's axle-loads are lower than you think and that you can safely alter your present pressures as a consequence. Up to you of course, but why suffer a harsh ride on rough roads unnecessarily when, for a little effort and research, you could have a smoother one? (Your 'handling' comment was interesting. It's probable I ran the Hobby for a couple of hours with the right rear tyre well down on pressure and I can't say I noticed any significant worsening in handling either.) Ian: I had a vague feeling a 2001 Duetto might have normal valves (ie. non-HP ones), but I could well be wrong. What's on your spare wheel? Philo: I'm a bit wary of the idea that HP snap-in valves as a species locate less well in a wheel, though I can well believe they may need more care when being fitted. I hesitate to say this, but I've been confidently told plenty of things by 'professionals' in my time, many of which were patently crap. Worth saying too that HP snap-in valves aren't just used on Transits - some (all?) Renault Masters have them too.

[handyman]

as ford changed the base model sometime early 06 (i think, as i have seen 06 new style ford transits) i presume euramobil would have to get all the fords they needed for the 06 model, before the change. They need the spec for the 06 model to be the same for the whole run? They cant get old base models for ford if they have stopped building them? If this is the case they would get all 05 built base models for their 06 model.(which they start building in summer 05 for launch september 05, sold as the new 06 model) I didnt know the weight of 2.9 included 2 persons, water, diesel and gas. (all together is quite heavy)So with this in mind I'd say the van has about 200kg odd of extra weight in it (bike rack, 2 bikes, awning, extra battery and then all the usual stuff) A lot of this weight is over the back wheels (garage full and bikes) Still, i have now dropped the pressure to 5 bar, cheers B-)

[Derek Uzzell]

handyman: Coachbuilt motorhomes built on a Transit Mk 6 FWD platform-cab chassis began to be marketed in mid-2004 - I think Chausson's Welcome 74 model was the first. Then Eura-Mobil released Profila, followed by offerings from Hobby, Hymer, Eriba, etc. When I was looking for a new motorhome I inspected quite a few of such 'vans during the period mid-2004 to April 2005 and all of them wore Michelin XC Camping tyres. But, from July 2005 (when I took delivery of my 2006-model Hobby), the XC Camping pattern appeared to have been replaced ubiquitously by Continental's Vanco-8 tyre. This observation led me to conclude that any 2006-model motorhome using this chassis would not have 'camping' tyres, but clearly I was wrong. Although the conversion part of a 2006-model Profila differs from that of earlier Profila versions (eg. the external decals are different), it would, theoretically, be possible to produce a 2006 Profila using a 2004 chassis. (In fact, I believe that bodywork 'mounting points' on current Mk 7 Transits are unchanged from the Mk 6, allowing motorhome manufacturers to switch bodywork designs seamlessly between 'old' and 'new' Transit versions.) The date of manufacture of a motorhome's original equipment tyres is usually not long before the date of manufacture of the motorhome's chassis. However, there can be a yawning time-gap between the latter date and when the conversion to a motorhome took place. This is not a hard-and-fast rule, just a rule of thumb. Anyway, it's always useful to know how old your tyres are. The Mass In Running Order (MIRO) of a Hymer motorhome in basic, standard form includes allowances for a driver (75kg), filled fuel tank, filled fresh water tank, 100% gas capacity and a 230V hook-up cable. A Hobby's MIRO varies slightly in formula as the allowances included for fresh water and gas are 90% of available capacity. Eura Mobil's brochure just says that the MIRO figure includes allowances for "driver, gas and water reserves, power supply", but the gas and water allowances will be at least 90% of maximum capacity. Note that there's NO allowance in the MIRO datum for passenger(s) weight, nor any allowances for factory- or dealer-fitted options (awning, bike-rack, extra battery, etc.) or 'luggage'. Your bike-rack + bikes will obviously load up just your motorhome's rear axle (and reduce front-axle static loading), while your passenger's weight will transfer mostly to the front axle. Distribution of awning weight will perhaps be 30% front-axle/70% rear-axle. I thought the 622SB had a permanent longitudinal rear bed rather than a 'garage', but, whatever the case, anything stored above or behind the rear-axle will place additional load on it. I still think you could safely drop the inflation pressures of your motorhome's rear tyres down to 4 bars. Conversely, if you are using 3 bars pressure for the front tyres, I think you may (possibly) need to increase that figure. But that's just guesswork and only weighing your motorhome will confirm whether it's a good or bad guess. If you are interested, there's a list of weigh-bridges on http://www.chrishodgetrucks.co.uk/pageweighbridge/weighbridgeshome.htm Ian: I've looked at Auto-Sleepers and Ford Transit literature and changed my mind! I now believe 2000-onwards Duettos will have the tyre-valve that has been failing. Besides which, your comment about your valves' inability to hold pressure beyond 20psi matches my own experience. General: I live near a small town that has 3 tyre-fitting outlets - an ATS branch and two privately-owned firms. I visited each outlet yesterday and asked about tyre-valve failure on Year 2000-onwards Transits. They all told me this was common knowledge within the industry. They all had replaced failed valves - the chap at ATS said they had replaced "hundreds" (which I took to mean "lots"!) All the failed valves were the HP snap-in type fitted to the Transit as original equipment. Everyone I spoke to expressed a dislike of this type of valve, but I'm sure this is because they are lumping all HP snap-in valves together when, in fact, it's just the specific make/model of valve fitted to the Transit that's failing. One fitter suggested that it's the HP valve's combination rubber/metal construction that's the culprit, but ordinary non-HP valves are similar in principle. Two of the tyre outlets admitted to replacing failed HP valves with non-HP ones as standard practice. It's now evident, I believe, that the few isolated Transit motorhome-related incidents that have been reported are the thin edge of a pretty thick tyre-valve failure wedge. I reckon there must be a lot of tyre-valves out there living on borrowed time. I've been told that Auto-Sleepers has liaised directly with Ford regarding this problem, but I've no information about the outcome. It's likely there are quite a few forum readers who own Auto-Sleepers Transit-based motorhomes fitted with these tyre-valves, so perhaps it would be in their own (and other everybody else's) interest to contact Auto-Sleepers and/or their A-S dealerships and make their concerns known.

[Guest JudgeMental]

it's straightforward to determine true chassis build of vehicle before buying. Just take note of VIN on dash, this is long mix off letters/number on small plate and call Ford or other manufacturer, and they will tell you exact build date (chassis not camper body)

[handyman]

[QUOTE]Derek Uzzell - 2007-10-06 9:42 AM The Mass In Running Order (MIRO) of a Hymer motorhome in basic, standard form includes allowances for a driver (75kg), filled fuel tank, filled fresh water tank, 100% gas capacity and a 230V hook-up cable. A Hobby's MIRO varies slightly in formula as the allowances included for fresh water and gas are 90% of available capacity. Eura Mobil's brochure just says that the MIRO figure includes allowances for "driver, gas and water reserves, power supply", but the gas and water allowances will be at least 90% of maximum capacity. Note that there's NO allowance in the MIRO datum for passenger(s) weight, nor any allowances for factory- or dealer-fitted options (awning, bike-rack, extra battery, etc.) or 'luggage'. Your bike-rack + bikes will obviously load up just your motorhome's rear axle (and reduce front-axle static loading), while your passenger's weight will transfer mostly to the front axle. Distribution of awning weight will perhaps be 30% front-axle/70% rear-axle. I thought the 622SB had a permanent longitudinal rear bed rather than a 'garage', but, whatever the case, anything stored above or behind the rear-axle will place additional load on it. I still think you could safely drop the inflation pressures of your motorhome's rear tyres down to 4 bars. Conversely, if you are using 3 bars pressure for the front tyres, I think you may (possibly) need to increase that figure. But that's just guesswork and only weighing your motorhome will confirm whether it's a good or bad guess. If you are interested, there's a list of weigh-bridges on .[/QUOTE] derek, You can see how my van can have camper tyres on it. B-) My van has a fixed bed at back, with garage at the back behind rear wheels. I believe this may be your favourite subject ;-)

[KD]

where is brian kirby by the way, i havnt read any of his words of wisdom in ages

[Guest JudgeMental]

[QUOTE]K&D - 2007-10-07 7:59 PM where is brian kirby by the way, i havnt read any of his words of wisdom in ages[/QUOTE] Away on Hol's in his new Hobby van...

[KD]

cheers eddie mate

[Brian Kirby]

Well hello Chaps and Chapesses.  This seems to be a bit of a can of worms, don't it?

On the question of tyres, Ford and Hobby; the Hobby handbook (see, I've been reading it!) says, I quote, "In principle we try to equip all vehicles with Michelin Camping tires (sic).  In times of high demand, however, Michelin is unable to fulfil all demands.  In this case, alternative brands are mounted, e.g. Pirelli." 

In the accompanying Hobby tyre pressure chart for 215/75 R 16C tyres, pressures are to be 3.5 bar front and 5.5 bar rear if Michelin, but otherwise 3.5 bar front and 4.75 bar rear.  Clearly these rear tyre pressures - also repeated in the Transit handbook (yawn, more reading!), but without the rider about fitting Michelin as a first preference - are not set for the maximum rear axle load (2250Kg), but are the pressures that will give the maximum load carrying capacity for the respective type of tyre fitted.  Presumably those for the front are set for the maximum front axle load of 1750Kg.  This seems to imply a mute acceptance by Ford/Hobby that the rear axle is liable to be overloaded (probably true!), so they recommend running the tyres at their maximum respective pressures, to ensure they can cope with the overload.

If, as Derek suggests, we are good boys and girls and check our axle loads at a weighbridge and then cosnult the tyre maker with the results, we should be able to reduce they tyre pressures and gain an improvement in ride comfort and, from my own experience, directional stability and general handling as well.

However, it seems unlikely, based on Derek's unfortunate experience, that running at reduced pressures will alleviate the problem with these pesky valves.  Questions for Derek.  Having found two more or less flat tyres on a motorway services, what happened next?  Did a recovery unit turn up, or was there a tyre bay at the services, and did you get clamp in valves fitted to replace the snap in ones?

Evening all!

[Dave Newell]

Welcome back brian :-D D.

[Derek Uzzell]

Brian: When I discovered one of our motorhome's tyres was partially deflated, we weren't on a motorway service area but on the "aire de services camping-car" at Ducey, near Avranches. I telephoned the RAC who contacted a local breakdown service. It was Saturday late-afternoon, so, other than assess the situation, the breakdown chap could do nothing until the following Monday morning when he returned and took the wheels with the failed valves to a tyre-fitting company on the outskirts of Avranche. I had asked whether 'metal' (ie. clamp-in) replacement valves could be installed. The ones used were not the type I had anticipated and I wondered if they were, in fact, suitable for a Transit wheel. I also had serious concerns over the fitting method employed. However, a leak test indicated that a seal between valve and wheel-rim had been successfully achieved and we drove back home without further incident. Subsequently I confirmed my suspicions that the valves fitted in France were incorrect and they have now been replaced (together with the valves on my motorhome's other three wheels) with different-design clamp-in valves. The chances of clamp-in tyre valves suitable for a Mk 6 Transit (the model type on which these valve failures are occurring) being stocked by a tyre-fitting company are essentially nil - there is just no call for this type of valve. The valves now fitted to my motorhome are manufactured by a German company named Alligator Ventilfabrik (www.alligator-ventilfabrik.de). The particular valve is Alligator's Part No. 512563 and details of it are on: http://www.eha-ventilfabrik.de/en/kat/uid_kategorien/0000866/id_matchcode/pkw_mv_113/bop/0/print/false/chksum/3bbd3366fa9f10c77a7f1e0be458c8ca/beetools.html I obtained the valves from a UK automotive equipment distributor named Auto4 (website: www.auto4.co.uk Tel: 01623 441800). The valve I chose is Auto4 Part No. 2563 shown in the "Metal Clamp-in Valves" section of the Auto4's downloadable pdf relating to valves. Total cost (including VAT + P&P) for 6 valves (5 + a spare) was £21. Installing the valves presented little difficulty. The tyre-fitter depressed the tyre's side-wall on the tyre-valve side of the wheel, removed the old valve and inserted the Alligator valve. A clamp-in valve will normally be installed in a 'naked' rim (ie. with no tyre present) and the Alligator valve has a screwdriver slot in its base to allow the valve's body to be held immobile while the outer nut is tightened. In my case, with the tyre still in place, the tyre-fitter needed to use mole-grips to hold the base of the valve steady. (I've seen examples of clamp-in valves that had no screwdriver slot or spanner-flats on their bases, so I suspect the mole-grips technique is commonplace.) Alligator's data for valve 512563 gives an installation torque-setting of 4-6Nm (2.95-4.43 ft.lbs), but it's doubtful that a tyre-fitter will have a torque wrench able to handle such low settings. The important thing is that the fitter doesn't massively over-tighten these valves. The extra weight of the clamp-in valves meant that the wheels needed to be re-balanced.