New tyre blowout

[tonyishuk]

Manhole cover / frame ?

 

Where a badly maintained road with a loose material around the m/hole frame and expose the sharp edge of the frame. This can occur on a manhole (or BT Duct M/hole) where water has pressurized inside the manhole an burst out around the frame washing out the roading material.

 

Our area has several "pothole / manhole"s similar to the above, One where the complete frame was lifted out of the road.

 

Rgds

 

[George Collings]

I walk a fair bit on roads and one of the worrying noises you hear is a clank when a vehicle drives over a manhole cover (or should that be a personhole cover). It indicates movement twixt cover and frame and that the road surface around the frame is being hammered and the cover is likely to crack or frame dislodged in the near future.

 

Reporting them to the highway authority in the past has seen fairly prompt remedial action. This winters weather and the cut backs my have have changed that.

 

Watch the roads and preferably don't drive when its raining when you can't see how deep the hole is to take avoiding action.

[colin weston]

I never realised that replacing a set of tyres could be so complex. Having decided to replace my 7 year old Michelin 225/70 R 15C tyres on my Autocruise Starburst following my tyre valve problem I have followed various threads with much interest. As this is the first time I have replaced tyres on a motorhome I decided I should first check my handbook and other supplied documents for recommendations. My Autocruise handbook makes no reference to tyres at all. My Peugeot Boxer handbook says refer to the label in the front door shut which shows the size 225/70 R 15 and the relevent front and rear pressures of 59.5 and 65.3 psi respectively. A 'C' designated tyre is not indicated. With the lowered AL-KO chassis I have always been impressed with the handling of the van and the performance of the tyres and am careful not to exceed the maximum front and rear axle loads of 1850 kg and 2000 kg respectively, within the MAM of 3500 kg. With a maximum load rating of 1120 kg at 65 psi the tyre loads on the rear axle have a 'safety factor' of some 12%, assuming correct tyre pressures are maintained. As I usually cruise on Motorways at 60 mph and the van is seldom fully loaded I don't tend to worry unduly although I make an effort to avoid any potholes and sunken drains, much to the consternation of my wife. Checking on the Michelin website I found that the replacement tyre recommended is the Agilis+ which does not have a 'C' rating. Recommended tyre pressures are the same. I note that the Hankook RA18 would also seem to be a suitable replacement, being somewhat cheaper than the Michelin. From the tyre labelling information both tyres seem to have equivalent grip and noise ratings but the fuel economy rating for the Michelin Agilis+ is C, whereas the Hankook RA18 is E. Doing some research on what the difference is, in real terms, the Goodyear site states that each difference is worth some 3% in fuel economy but the 'D' rating is not used. Does this mean that the difference between 'C' and 'E' is 3% or 6%? Has anyone researched these ratings in detail? The German article on Hankook tyres looked interesting but I had difficulty get a translation.

[Brambles]

....but but but Colin, I come up with the same info as you...but seems to me to be meaningless as tyre size they selected is a 205 and not a 215 which I have.

[Derek Uzzell]

colin weston - 2014-01-31 10:58 AM

 

I never realised that replacing a set of tyres could be so complex. Having decided to replace my 7 year old Michelin 225/70 R 15C tyres on my Autocruise Starburst following my tyre valve problem I have followed various threads with much interest. As this is the first time I have replaced tyres on a motorhome I decided I should first check my handbook and other supplied documents for recommendations. My Autocruise handbook makes no reference to tyres at all. My Peugeot Boxer handbook says refer to the label in the front door shut which shows the size 225/70 R 15 and the relevent front and rear pressures of 59.5 and 65.3 psi respectively. A 'C' designated tyre is not indicated. With the lowered AL-KO chassis I have always been impressed with the handling of the van and the performance of the tyres and am careful not to exceed the maximum front and rear axle loads of 1850 kg and 2000 kg respectively, within the MAM of 3500 kg. With a maximum load rating of 1120 kg at 65 psi the tyre loads on the rear axle have a 'safety factor' of some 12%, assuming correct tyre pressures are maintained. As I usually cruise on Motorways at 60 mph and the van is seldom fully loaded I don't tend to worry unduly although I make an effort to avoid any potholes and sunken drains, much to the consternation of my wife. Checking on the Michelin website I found that the replacement tyre recommended is the Agilis+ which does not have a 'C' rating. Recommended tyre pressures are the same. I note that the Hankook RA18 would also seem to be a suitable replacement, being somewhat cheaper than the Michelin. From the tyre labelling information both tyres seem to have equivalent grip and noise ratings but the fuel economy rating for the Michelin Agilis+ is C, whereas the Hankook RA18 is E. Doing some research on what the difference is, in real terms, the Goodyear site states that each difference is worth some 3% in fuel economy but the 'D' rating is not used. Does this mean that the difference between 'C' and 'E' is 3% or 6%? Has anyone researched these ratings in detail? The German article on Hankook tyres looked interesting but I had difficulty get a translation.

 

Whatever tyre were chosen for your motorhome, it would need to carry a "C" (Camionette) or "CP" (Camping Pneu) suffix to show that it had been designed to be suitable for light-commercial vehicle or motorhome usage.

 

So a 225/70 R15 C or 225/70 R15 CP tyre, but not a 225/70 R15 (no suffix) tyre as this might have been designed for another type of application altogether and unlikely to have the necessary load-carrying capability - for example, this all-terrain Bridgestone tyre

 

http://www.oponeo.co.uk/tyre-details/bridgestone-dueler-a-t-694-225-70-r15-100-t

 

Michelin's website may not specify that the "Agilis+" pattern is "C"-suffixed, but it is. As all Agilis tyres are shown in the "Van" part of Michelin's website, the company may feel it unnecessary to highlight that the tyres have a "C" suffix. (I note that the "CP" suffix does not seem to be mentioned on the Agilis Camping part of Michelin's website, but this tyre definitely does carry a "CP" suffix.)

 

The 2013 promobil article I referred to earlier involved six tyre patterns, all in 215/70 R15 size with a 109 Load Index. Two of the tyres were "CP" suffixed and four were "C" suffixed.

 

Four of the tyres had a 'fuel economy' letter of "E" and two of "C". Rolling resistance was measured and the Michelin Agils+ was significantly best (hardly surprising as 'fuel economy' is an important selling point with this tyre). The other tyre with a "C" fuel economy letter was Hankook's Vantra LT RA18 that was 4th on the rolling-resistance league-table. Of the 11 separate tests promobil carried out Hankook's RA18 (95€) proved superior or equal to Michelin's Agilis+ (127€). The only test where Agils+ had a significant advantage over RA18 was the rolling-resistance test. (Conclusion - If economising on fuel is paramount, go for Agils+: if reducing the risk of an accident is more important, go for RA18.)

 

For your Autocruise motorhome the appropriate Hankook Vanta LT RA18 tyre specification would be 225/70 R15 C 112/110S. This tyre's labelling is C/B/70dB as shown on Hankook's website and on this advert

 

http://www.blackcircles.com/order/tyres?&width=225&profile=70&rim=15&speed=S

 

In your case the choice seems straightforward. It's got to be Hankook's Vantra LT RA18.

[tyreman]

i would be very suprised if it was a rougue tyre but only very close examination at the factory is going to find out and i doubt you will ever be told the reason,your tyre company have given you excellent service as the norm with a tyre problem is that you would have to pay for a new tyre while the alleged faulty tyre is returned to the factory and if found to be at fault you would be reimbursed on the amount of tread worn.

For what its worth it could well be a fitting fault as i have seen bulges appear on sidewalls of a couple of tyres where the heel of the fitting machine has worn to a sharp edge due to lazy tyre fitters not removing the steel weights before removing the tyre and this sharpens the heel and when fitting a tyre if the tyre rim is not pushed down into the well of the wheel the heel of the fitting machine can cut the base of the tyre rim and when inflated air can find its way in between the sidewall plies and cause a bulge....with 80psi behind it,it wouldnt take long for it to pop.........i'm not saying for one minute that this has happened,just a theory.

[Derek Uzzell]

Derek Uzzell - 2014-01-31 4:43 PM

 

...Of the 11 separate tests promobil carried out Hankook's RA18 (95€) proved superior or equal to Michelin's Agilis+ (127€)...

 

Having glanced back through my last posting I realise that the above sentence should have read

 

"...In 10 of the 11 separate tests promobil carried out, Hankook's RA18 (95€) proved superior or equal to Michelin's Agilis+ (127€)..."

 

 

[colin weston]

Thanks for the clarification Derek. The cost saving of around £150 can buy a fair amount of fuel, about 24 gallons. At 30 mpg, my typical fuel consumption, this equates to 720 miles. Assuming my normal average mileage of 5000 miles and a tyre life of 7 years the Michelin tyre would need to give a fuel economy advantage of some 2% to equate to the Hankook purchase on purely economic terms.

I did note earlier that the Michelin CP is only recommended for vans that were homologated with such a tyre, so these would not be suitable for my van.

[Brian Kirby]

Colin, if I'm understanding you correctly, I think you may be misinterpreting the recommendation for fitting CP tyres to vehicles originally homologated with them. IMO, all this recommendation should be taken to mean is that in Michelin's opinion, a CP tyre should be replaced with a CP tyre. This is not bad advice.

 

The more cynical among us, noting that Michelin are one of only three manufacturers who make CP tyres, might mutter - "well they would wouldn't they?" :-)

 

However one may view that attitude, it should be remembered that a) it is a manufacturer's recommendation, and b) it does not imply that CP tyres should not be fitted to motorhomes originally supplied on C tyres. If CP tyres actually have the benefits claimed for them, those benefits would transfer to any motorhome so equipped.

 

Our Hobby Van, like Derek's van, was delivered shod with C tyres. Other Hobby Vans, identical in all respects to ours, were delivered shod with CP tyres. Both types of tyre were of the same size, section, speed, and load rating. The CP tyre, however, has higher recommended pressures than the C type, for the same axle loads. The same is true for a few other vans, and I see no general reason to stick rigidly to either C, or CP, tyres, merely because that was the type originally fitted.

 

The exception I would make is where a van runs close to its maximum permissible axle loads (for example, where it has been re-plated without increasing the tyre load rating), and was originally CP shod. Then, I would replace like for like. However, any van that is comfortably within its MAM, and its individual axle maxima, can IMO, reasonably be fitted with either tyre type, on the strict proviso that they are of identical size and section, and have equal or superior load and speed ratings.

[Derek Uzzell]

The advice Michelin provides regarding "CP" tyres is based on recommendations made by the European Tyre and Rim Technical Organisation (ETRTO). 

In April 2013 ETRTO made the following motorhome-related recommendations:

Tyre use and maintenance for motor-caravans (or motor homes)

Fit the right tyres 

As with all road vehicles, it is essential that tyres of the correct type be fitted.

Tyres usually fitted to motor-caravans are of a "light commercial” type.  

CP type-tyres (commercial vehicle tyres for service on motor-caravans) have only been marketed in the last few years. This followed a study which demonstrated that overloading is generally the main cause of tyre failure, due to the fact that this type of vehicle often carries an excessive or badly distributed load which may be higher than that permitted by the load index (LI) of the tyre, usually on tyres fitted to the rear axle.

CP-type tyres have been designed to cater for the higher loads imposed by motor-caravans, especially when fitted in single formation on the rear driven axle (also see following comments below referring to the “service description”).

It is always advisable to have the same type of tyres on all wheels and axles. Only tyres of the same size and service description (load index / speed symbol) and identical wheels should be fitted across an axle and carried as a spare. Tyre pressures across an axle should be equal. Additionally, any deviation from the original type of tyre is likely to have an effect on the handling and general characteristics of the vehicle. For these reasons, it is strongly recommended that motor-caravans are only fitted with CP-tyres.

Therefore, before changing the type of tyre, always consult either the vehicle or the tyre manufacturer.

When fitting any new tyre size differing from the original equipment, it is the user's responsibility to ensure compliance with existing regulations, regarding specifically, the vehicle’s load and speed capability. Never replace tyres with those of a lower speed rating or lower load capacity.

Referring to the "service description"

The LI designation of CP-type tyres carriesa single ‘load index’ indicating their normal use in single fitment. In this case only, tyres on the rear axle have to be inflated to 550 kPa, (to compensate for severe conditions of unequal load distribution, but with no further concession to increase the maximum load capacity). When these tyres are used in dual fitment, a tyre pressure increase is not required and the axle load capacity is calculated as 1.85 times that of a single wheel fitment.

General recommendations for motor-caravans(or motor homes)

Check the pressures

It is essential for the safety and stability of the vehicle that all tyres are correctly inflated. Incorrect tyre pressures do not only adversely affect the handling, but can also cause dangerous tyre failure. The correct inflation pressure for motor-caravan tyres will be shown in the vehicle / chassis handbook.

Furthermore, tyres that are not inflated to the correct pressure may wear rapidly and adversely affect the fuel consumption of the vehicle. Therefore, in the long run, keeping them at the right pressure could also save money. Pressures should be checked and, if necessary, adjusted prior to any journey when the tyres are cold - not after being driven when they will be higher. Never reduce tyre pressure when the tyre is warm, as the pressure may be too low when the tyre cools. After checking the tyre pressure, ensure that the valve is not leaking and that a valve cap is fitted.

Tyre care

Check your tyres regularly but particularly when the motor-caravan has not been used for some time. Vehicles that are not normally used during winter should be thoroughly inspected prior to re-use. Inspect for any sign of deterioration in the tyres such as sidewall cracking and/or carcass deformation. Tyres fitted to a stationary vehicle, particularly if parked in coastal areas may deteriorate more quickly over time than those in regular and frequent use. If a motor-caravan remains stationary (parked) for a length of time, it is requested to cover the tyres in order to shield them from direct sunlight and, if possible, jack the weight off them. If in doubt about the condition of your tyres, have them checked immediately by a tyre specialist.

Although Continental appears to take a less didactic view than Michelin regarding advertising the ETRTO's advice about motorhome tyres, Continental's Technical Handbook will show that Continental recommends similar high inflation-pressures for their "CP"-type tyres when these are fitted to a vehicle's rear axle.

[colin weston]

Hi Brian and Derek,

I guess we could keep this thread going forever! However, two things spring to mind. I know earlier that someone raised the question of insurance cover if one were running with wrong tyre pressures. IMHO if someone chose to do a roadside weight check and tyre pressure check, maybe at a ferry port or after an accident, and they find your tyre pressures are significantly higher than those indicates on the vehicle decal it might take a long time to explain that you are running on improved high pressure tyres.

I would also wonder how the ride and handling might be affected by running at significantly higher tyre pressures, although potentialy handling might improve. I do know that the ride comfort in my van varies considerably between being 'unloaded' when it has it's winter runs locally to keep it 'fit' and when it is more heavily loaded for trips to mainland Europe as I keep my pressures at 59/65 psi regardless of load.

I can understand why the CP tyre was developed as my previous van was an Autocruise Stardream with a rear lounge and as the majority of low-down storage was at the rear much care was needed to avoid exceeding the rear axle weight limit. This was one of the reasons that I bought my current van as the load distribution is much better.

[Brian Kirby]

I don't think higher pressures than those quoted either on the vehicle decal or in the handbook are necessarily wrong Colin.

 

If one looks at the tyre manufacturer's technical databooks for the tyres on one's van, or at the Tyresafe publication on motorhome tyres, one will find a list of tyre pressures suitable for various axle loadings. These are in fact the "correct" pressures to use, if one wishes to ensure that the tyre pressures are appropriate for the job the tyres are doing. For example there are different pressures for front and rear tyres for the same axle load, to take account of the different tasks demanded of tyres in these positions. These charts also state the maximum pressure to which the tyre may be inflated, and the valve type appropriate to the various pressures.

 

Motorhome manufacturers merely state the pressures appropriate for the maximum permissible front and rear axle loads. They have to do this as they cannot foresee how a van will be loaded in use: it is the fail-safe option, adopted on the basis that a tyre that is technically over-inflated for its load is "safe". It may create a harsh ride, or a bit of tramilne wander, but the tyre won't fail as a result. The danger is under-inflation relative to load, which can cause a tyre to overheat and catastrophically fail.

 

If one weighs one's van fully laden, and notes the axle loads, one can reasonably elect to use the tyre manufacturer's recommended pressures for those loads, matched to the tyres actually fitted. This tends to remove some of the harshness of the ride, and in my experience also improves directional stability on uneven roads. If one finds the ride unchanged, or other aspects of driving are adversely affected by the lower pressures, on is at liberty to revert to the 'van manufacturers pressures.

 

What the tyre manufacturers realised some years back, and I think alerted ETRTO to, is that many motorhomers do not check the axle loads of their vans, so unwittingly overload (mainly the rear axle). This overloading has led to catastrophic tyre failures, because an overloaded axle implies an underinflated tyre. So, they have developed a range of tyres designed primarily to be proof against this kind of inadvertant overload. The tyres have other claimed advantages, mainly, I think, to disguise or excuse the fact that their primary purpose is to cope with overload. The reason for this subterfuge is fairly obviously the risk inherent in saying, in effect, "hey, it's OK to overload your van". :-)