I Thought Changing A Tyre Would Be Easy.... (1 Viewer)

[rosalan]

I really did think it would be easy but...
At the Motorhome Show in Newark, I had our van weighed for free! They told us that we were 30kg overweight at the rear but not to worry, as we had air suspension fitted it would be possible to change my rear tyres from 215/70 R15 to 225/70 R15 which have a wider tread. Not really understanding how our axle could have increased payload, I asked our Dethleffs dealer who explained they are concerned with the habitation component, so I contacted Continental Tyres who explained that they do not make a Vancocamper tyre in this size, only Fiat could tell me what tyres were permissible. In all fairness they tried to help, after three phone calls from Italy I spoke to their manager concerned with motorhomes. This person said that only Dethleffs could advise on the right tyre to take a greater load. By now I was beginning to enjoy my query so I telephoned Sci Tech who had weighed the vehicle in the first place. Their response was outstanding. They told me which tyre to fit (225/70) and what pressure to put into them (65lb all round), something they knew because they had tested the tyres on motorhomes.
What did surprise me were the number of people who had said that tyres were not their problem.
Alan

 

[funflair]

Looks like a 112 load rating, your 215 will be 109 I guess. They right in that they don't do the camper in that size so it's a white van tyre.

Martin

 

[DuxDeluxe]

Looks like a 112 load rating, your 215 will be 109 I guess. They right in that they don't do the camper in that size so it's a white van tyre.

Martin

Yep, only Michelins. I had the same problem when looking for camping tyres uprating the pilote

http://www.tyreleader.co.uk/car-tyr...ripAll=on&lwetAll=on&lnoiseAll=on&orderby=pop

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[funflair]

Yep, only Michelins. I had the same problem when looking for camping tyres uprating the pilote

http://www.tyreleader.co.uk/car-tyr...ripAll=on&lwetAll=on&lnoiseAll=on&orderby=pop

Personally not worried about camping tyres, the side walls and overall tyre weight of our Continental fourseasons is far greater than the prope camping ones, mind you they are 121 load rating and the campers only 116 I think.

Martin

 

[tony_g]

Michelin will routinely advise 80psi on the rear for the 225/70 R15 Agilis CP 112, irrespective of the max axle loading you enquire about. This is the max pressure advised for these tyres and my experience is that they still appear to have a slight bulge. However, they seem to do a good job. Curiously, though, they advise 65/70psi on a front axle which has the same max load potential as the rear (although they could not be at these loads simultaneously).

 

[autoswan]

Probably a silly question but when pumping up to those pressures is it best to do it when the mh is unloaded / empty or doesn't it matter ?

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[2657]

I would have thought that if you are 30 kg overweight to the max weight shown on the VIN plate then you will still be legally overweight even if the tyres are uprated, surely an upgrade to a higher max weight would be needed.

Changing the tyres to a higher weight capacity will make things safer but still not legal, just my opinion.

 

[Steve]

I would have thought that if you are 30 kg overweight to the max weight shown on the VIN plate then you will still be legally overweight even if the tyres are uprated, surely an upgrade to a higher max weight would be needed.

Changing the tyres to a higher weight capacity will make things safer but still not legal, just my opinion.

I think you are right over wieght is over weight. type of tyre is a problem of its own. if vin plate says xxx then xxx it is.
Steve

 

[Puddleduck]

I would have thought that if you are 30 kg overweight to the max weight shown on the VIN plate then you will still be legally overweight even if the tyres are uprated, surely an upgrade to a higher max weight would be needed.

Changing the tyres to a higher weight capacity will make things safer but still not legal, just my opinion.

Thanks for that post - I thought it was just be being stupid and girlie....... what is on the VIN plate is what determines overweight although an upgrade might involve tyre changes etc. Or am I missing something ? (okay, I know, half a brain is missing just for starters)

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[rosalan]

I agree absolutely, overweight is overweight and SVtech did look at my plate, that was an original Dethleffs upgrade to 3.85 but still gave me the advice that I have followed. I would be very happy to have someone explain to me why I am now ok! My guess is that the weight allowed on the rear axle may exceed the maximum tyre load capacity. They were particularly concerned that I must have air suspension at the back. Again I do not know why. It is also the tyre footprint that increases with my new tyres.
Alan

 

[2657]

I agree absolutely, overweight is overweight and SVtech did look at my plate, that was an original Dethleffs upgrade to 3.85 but still gave me the advice that I have followed. I would be very happy to have someone explain to me why I am now ok! My guess is that the weight allowed on the rear axle may exceed the maximum tyre load capacity. They were particularly concerned that I must have air suspension at the back. Again I do not know why. It is also the tyre footprint that increases with my new tyres.
Alan

That may well be the case, I would check the max rear axle load on the VIN plate and compare with the max load rating for the tyres.The max load for each tyre is on the tyre together with the recommended pressure for that load or the load can be worked out from this table:

http://www.ctyres.co.uk/tyre_info/tyre_load_index.html

If the vehicle has been uprated by having air suspension fitted and the tyres have not been changed to cope with the increased weight then I would consider that a serious error on the part of whoever did the upgrade.

This is only my opinion and whilst I have some experience with vehicle weights I am not an expert and my comments remain simply my opinion.

 

[rosalan]

The uprating was done by Dethleffs in Germany and the tyres fitted originally were 215/70 r15 109. I had the air-suspension fitted to prevent the back of the van touching the road on severe hairpins (after three times 'bottoming' last year). As I indicated, I do not understand why I am now well within weight limits.
Alan

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[Emmit]

Without checking from memory, 215x 70x 15 @109 load rating would give you a load capacity of1030kgs per corner, front and rear.
I don't know what your Dethleffs weighs front and back.
We changed our 'Camper 'tyres to van tyres when we uprated and I could kick myself for not investigating further and getting 225's to get an even greater safety margin.

 

[JimboT]

Is this really a big deal ?
Everything is made with a factor of safety you are most likely well within that.
I bet if you took three results of weight you will get three different results.
In short 30kg is less than 1% if you are 10% 385 kg that maybe an issue.
increasing tyre pressure to 75 psi instead of 69 PSI would cover this.
I would no be concerned with 1%
Jim

 

[TerryL]

Having gone through the weight upgrade myself, I had to read the posts a couple of times before I understood the O/P question. In particular the point about changing the tyres to make it legal, so I compared it with my own experience on our Bolero.

When I upgraded from 3500kg to 3850kg, SvTech told me I needed air suspension assist on the rear and uprated tyres, that is, increased load factor. They advised that Continental Vanco2 (winter tyres, as I requested) at 225x70x15 (load rating 112) would be what I needed and provided me with a new plate that, amongst other things, showed the rear axle limit to be 2240kg. That equates to 1120kg per wheel, hence the 112 load rating - see how it works? At the time these were the only winter tyres available to give me that load rating, regardless of tread width, and would fit my rims.

I would guess that they advised you to change your tyres because those fitted did not meet the requirements of the plate weight (3850kg), regardless of whoever uprated the chassis from the Fiat standard 3500kg. Thus you were "technically" overweight - did by any chance the rear axle weight come out at 2210kg (2x 1090 plus 30)? You already had air-assist suspension so that bit was covered.

I subsequently asked Continental what pressures I should use, having given them all the details. They came up with 56psi front and 65psi rear, which I have now used for several years without problem. And just to reassure you, they do still "bulge" a bit so I bought a set of TyrePal sensors to keep an eye on them.

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[2657]

That equates to 1120kg per wheel, hence the 112 load rating - see how it works?

That is coincidence, none of the other load ratings work like that.
I would agree with the rest of your post and is more or less what I posted earlier but clearer and from someone with actual experience of an air assisted uprate.