Technical 215/70 R15 C tyre - not for motorhome?

[wanderer 888]

Hi there, it has been very difficult to obtain a spare wheel for my 2011 Fiat Ducato (Dethleffs) - I cannot believe they stopped supplying them in later models! I finally got one rim with a 215/70 R15 C tyre - which I am told is not for motorhomes - the ones marked CP are.

My question is, would it be OK to use this C version as a spare tyre? I imagine it would be fine to use on the front wheels, but not so much on the back because the tyre walls are not so reinforced?

If I did use it on the rear axle for an emergency, then it would most likely have only 50-100 kms to travel before fixing a flat tyre. Do you think it would safely hold a 3.5 tonne vehicle with about an extra 300 kg = 3.8 tonnes?

I have an Alco chassis, so I do not know if that makes much difference as the shock absorbers seem to be set up differently.

 

[jackwhoo]

Which motorhome tyres should I use? | MICHELIN UK

Everything you need to know about the best tyres for your motorhome and their pressure for safe driving.

www.michelin.co.uk

 

[jackwhoo]

What are the load index numbers on your c tyre ?

What are the load index numbers on your co tyres?

What is the maximum rear axle weight on vehicle plate?

 

[HughJampton]

As a spare for short distance use looking to replace with a permanent solution there should be no issue.

It needs to be the same profile as the CP tyres, have an appropriate load index (the same or higher than the fitted CP tyres), and be inflated to the appropriate pressure (which may well be below that recommended for the equivalent CP tyre which usually have higher quoted pressures).

Interestingly enough, I specified my Hymer with a spare - the standard tyres are CP, the supplied spare is C (albeit of reasonable quality). I queried this with the dealer, but also ultimately checked with stock Hymer vehicles elsewhere and the same applied - factory-fit.

I wouldn't choose to do much mileage with a mixture, but for emergency use I'm reasonably happy.

(BTW, I have had motorhomes fitted from the factory with non-CP tyres all round).

 

[wanderer 888]

As a spare for short distance use looking to replace with a permanent solution there should be no issue.

It needs to be the same profile as the CP tyres, have an appropriate load index (the same or higher than the fitted CP tyres), and be inflated to the appropriate pressure (which may well be below that recommended for the equivalent CP tyre which usually have higher quoted pressures).

Interestingly enough, I specified my Hymer with a spare - the standard tyres are CP, the supplied spare is C (albeit of reasonable quality). I queried this with the dealer, but also ultimately checked with stock Hymer vehicles elsewhere and the same applied - factory-fit.

I wouldn't choose to do much mileage with a mixture, but for emergency use I'm reasonably happy.

(BTW, I have had motorhomes fitted from the factory with non-CP tyres all round).

oh thats good to know, if its good enough for Hymer to use a C rated, then its good enough for me!

 

[HughJampton]

Given your statement on running at 3.8 tonnes, I'd be more worried about whether 215/70 R15 CP or C are adequate for the load. They're likely to be load index 109, and these would have a maximum axle load of 2060kg.

If you're running at 3.8 tonnes it is very likely the rear axle load will exceed 2060kg. That would be unsafe on Load Index 109 tyres of either c or CP rating (though there is a possibility that the CP tyres would cope with any overloading slightly better). It is also very likely that the vehicle's maximum rear axle load will be specified as 2000kg.

 

[wanderer 888]

Given your statement on running at 3.8 tonnes, I'd be more worried about whether 215/70 R15 CP or C are adequate for the load. They're likely to be load index 109, and these would have a maximum axle load of 2060kg.

If you're running at 3.8 tonnes it is very likely the rear axle load will exceed 2060kg. That would be unsafe on Load Index 109 tyres of either c or CP rating (though there is a possibility that the CP tyres would cope with any overloading slightly better). It is also very likely that the vehicle's maximum rear axle load will be specified as 2000kg.

I did run similar load on my previous motorhome for three years on Michelin CP's, no problem. Should try and find a weighbridge and see exactly what I am carrying, the above figure is just an estimate.

 

[Cornish Ian]

I did run similar load on my previous motorhome for three years on Michelin CP's, no problem. Should try and find a weighbridge and see exactly what I am carrying, the above figure is just an estimate.

Sounds like a good chance to check your actual weights, front, back and total against what your plate allows.

 

[jadatis]

As spare tire no problem.
Even when all tires where C no problem.

To my opinion CP is yust a marketing thing.
Respected brand Vredestein dont have CP.

Cp tyres of same size as C have same maxload at same pressure.
Your size is exeption Loadindex 109 at 65 psi, CP at 69 psi.

To my conclusions CP is introduced to cover overloading on rear axle at 80 psi, but official same maxload as C-tyre.
So motorhome maker can keep using the original rimms with maxload.

 

[wanderer 888]

As spare tire no problem.
Even when all tires where C no problem.

To my opinion CP is yust a marketing thing.
Respected brand Vredestein dont have CP.

Cp tyres of same size as C have same maxload at same pressure.
Your size is exeption Loadindex 109 at 65 psi, CP at 69 psi.

To my conclusions CP is introduced to cover overloading on rear axle at 80 psi, but official same maxload as C-tyre.
So motorhome maker can keep using the original rimms with maxload.

many thanks!

 

[jadatis]

I registered to this forum today, to react to this topic.

Motorhome-Van tyre pressures | FIAT Ducato

Starting to get confused about 'recommended' tyre pressures for my van Last week had new tyres fitted to my motorhome. Now I have always run the old Michelin tyres at 55PSI front, and 66PSI rear. Even tyre wear, reasonable (for weight) handling, and did not get too hot on long motorway drives...

www.fiatforum.com

https://www.fiatforum.com/threads/motorhome-van-tyre-pressures.501947/#post-4699281

In that same size in CP as here.
Made pressure /axleload list there for AT 69 psi, but you can also use it for your reserve C tyre AT 65 psi, wont give dramatic differences.

And search on sidewal of your tires, if both of Continental groop, for Maximium inflation pressure of 10 psi higher then maxloadpressure ( 65 or 69 psi), officially called reference-pressure.