Ouch!! (Tyres)

[Geek]

When people refer to varying loads on a tyre, this is a bit vague.
The load does vary a bit because of different amounts of stuff in the vehicle, but the load varies a LOT more when you go over bumps.

 

[TJBi]

Because lower pressures mean more sidewall flexing.
More sidewall flexing means more heat generation.
Thicker sidewalls means less heat dissipation.
More heat generation and less dissipation means higher temperatures.
Higher temperatures means more risk of blowouts.
Blowouts mean more risk of death.

If you look at the makers' charts, for C tyres, then pressures vary by loading. For CP tyres, regardless of load, it is usually '80psi unless the ride is too harsh, then 65psi'

Just don't buy CP tyres.

And do buy TyrePal!

 

[TeamRienza]

Another vote for tyrepal. Had it for 5+ years. Really useful in France last June when my back right wheel was binding due to faulty abs unit. The temperature reading at 70c as opposed to 29c for the other wheels allowed prompt diagnosis of a problem.

Davy

 

[trevskoda]

Just fix the problem then ....

Jeez bodgery of the finest degree

Tyre bay cannot find the leak, no budgies on my part.

 

[colinm]

If you look at the makers' charts, for C tyres, then pressures vary by loading. For CP tyres, regardless of load, it is usually '80psi unless the ride is too harsh, then 65psi'

Just don't buy CP tyres.

In my experience Continental are perfectly happy to advise on pressures in CP tyres dependant on loads, they are also happy to recommend certain of their C tyres for motorhomes, it is Michelin who will only recommend CP tyres for motorhomes, and only recommend maximum pressure for rear tyres, this is due to a court case brought against them after they recommended a pressure for a given axle load but the motorhome was subsequently loaded to a higher level.

 

[barryd]

In my experience Continental are perfectly happy to advise on pressures in CP tyres dependant on loads, they are also happy to recommend certain of their C tyres for motorhomes, it is Michelin who will only recommend CP tyres for motorhomes, and only recommend maximum pressure for rear tyres, this is due to a court case brought against them after they recommended a pressure for a given axle load but the motorhome was subsequently loaded to a higher level.

Conti have not replied to my email sent last Friday as yet regarding advising on tyre pressures for their CP tyres.

 

[colinm]

Conti have not replied to my email sent last Friday as yet regarding advising on tyre pressures for their CP tyres.

It's been 10 years since I last contacted Conti, so it's possible they have gone all 'elf and safety' since over pressures, but they still recommend a tyre for my van which Michelin refuse to do. They did have a online page showing recommend pressures, not sure if this is still available, and I'm sat in waiting room on me phone, I'll give searching for it a miss for now.

 

[mark61]

Because lower pressures mean more sidewall flexing.
More sidewall flexing means more heat generation.
Thicker sidewalls means less heat dissipation.
More heat generation and less dissipation means higher temperatures.
Higher temperatures means more risk of blowouts.
Blowouts mean more risk of death.

If you look at the makers' charts, for C tyres, then pressures vary by loading. For CP tyres, regardless of load, it is usually '80psi unless the ride is too harsh, then 65psi'

Just don't buy CP tyres.

That would be the same for most tyres, CP or not.

 

[Nabsim]

This could go on for ever. To my mind, if the tyres are correct size and meet the axle load ratings and have any other qualities you may need (3 peaks maybe) then I don't see a problem.

Tyres originally fitted to motorhomes are usually of a Light Commercial (“C” or “CP”) type. CP-type tyres are now widely used as they have been designed to cater for the higher loads imposed by motorhomes, especially when fitted in a single formation on the rear axle. The original tyre specification should not be changed without consulting either the vehicle or tyre manufacturer. Deviating from the original specification of tyre is likely to have an effect on the handling and general characteristics of the vehicle. Never replace the tyres with ones of a lower speed rating or load capacity.

https://www.tyresafe.org/wp-content/uploads/2017/08/Motorhome-leaflet-FINAL.pdf

 

[exwindsurfer]

Neil I've went from 225 x70 x15in 109/112 rated to 225 x 75 x16in 120/121 rated so it has raised the ride hight altered the gearing probable altered the geometry of the suspention and drive like a dream so what do you think lololol

Ps I run the tyres at 60psi all round+ the offset on my alloy wheel I have have given me a 3in wider track than standard.

 

[trevskoda]

Neil I've went from 225 x70 x15in 109/112 rated to 225 x 75 x16in 120/121 rated so it has raised the ride hight altered the gearing probable altered the geometry of the suspention and drive like a dream so what do you think lololol

Ps I run the tyres at 60psi all round+ the offset on my alloy wheel I have have given me a 3in wider track than standard.

3 ins offset will put a strain on the wheel bearings all round and alter the front geometery, this happens to folk who fitt wheel spacers, dont do this.
a line down through the centre of the tyre should be inbetween the front bearings, back the same.

 

[barryd]

This could go on for ever. To my mind, if the tyres are correct size and meet the axle load ratings and have any other qualities you may need (3 peaks maybe) then I don't see a problem.

Tyres originally fitted to motorhomes are usually of a Light Commercial (“C” or “CP”) type. CP-type tyres are now widely used as they have been designed to cater for the higher loads imposed by motorhomes, especially when fitted in a single formation on the rear axle. The original tyre specification should not be changed without consulting either the vehicle or tyre manufacturer. Deviating from the original specification of tyre is likely to have an effect on the handling and general characteristics of the vehicle. Never replace the tyres with ones of a lower speed rating or load capacity.

https://www.tyresafe.org/wp-content/uploads/2017/08/Motorhome-leaflet-FINAL.pdf

I have bookmarked this thread so in ten years time (hopefully) when my tyres need replacing ill look at it and never ever ever ever start another tyre thread.

 

[runnach]

I have bookmarked this thread so in ten years time (hopefully) when my tyres need replacing ill look at it and never ever ever ever start another tyre thread.

You’ll be treading on thin rubber in ten year time

 

[Canalsman]

Ps I run the tyres at 60psi all round+ the offset on my alloy wheel I have have given me a 3in wider track than standard.

Bad idea as outlined by @trevskoda

 

[exwindsurfer]

All I can say its has worked for over 10 years so why has none of theses faults show up ?

 

[mark61]

All I can say its has worked for over 10 years so why has none of theses faults show up ?

Because as long as you don't change the offset too much, the extra strain is minimal, but extra strain there is.

 

[alcam]

It has been suggested recently that there is an over emphasis on mental health diagnosis .
The analysis of tyres , batteries, b2fekkinB , mtwattingppt , lithium and whether you put daz or persil in your potty is , right royally , messing with the mental health of many on here . Well , me actually.
Just saying !

 

[Nabsim]

Neil I've went from 225 x70 x15in 109/112 rated to 225 x 75 x16in 120/121 rated so it has raised the ride hight altered the gearing probable altered the geometry of the suspention and drive like a dream so what do you think lololol

Ps I run the tyres at 60psi all round+ the offset on my alloy wheel I have have given me a 3in wider track than standard.

Not sure what I did but I had typed a bit more than is in my post. It should have said that the second paragraph was what Tyresafe.org had to say about it (C or CP tyres).

I will have to look when I go to the van but I think mine are not CP tyres but I can't remember. There were 2 options I could have, the four season (which I got) or the vancontact. The Vancontact are not CP but C.

The 1600 VW trike I had the rear brakes had been uprated to Golf GTI (I think it was) disks and pads, I had Chevrolet spacers to allow me to run some big Jaguar wheels and tyres. I never had a problem either Jeff. In fact as soon as you start to build a trike or a sidecar outfit the original geometry is out the window.