CP tyres and pressures. (1 Viewer)

Aug 19, 2013
3,001
4,332
Wells, Somerset
Funster No
27,611
MH
Elddis 115
Exp
since 2004
Prior to my present van I always had a PVC. Sorry, woosh bang. The current one is a small 3.3 ton Elddis plastic bodied with CP tyres. The last PVC was originally fitted with CPs, but because of the harsh ride I lowered the pressures a little and moved over to standard tyres when they came up to replacement, still with reduced pressure. Às such they travelled well and comfortably. The ride was much better. Now, on this van, with the CPs, I truly dislike the ride. When I bought it, the tyres only had 5k on them, and were 15 inch on alloys with 215/70, shorter wheel base, higher wider plastic body and higher tyre pressure. So now, the ride is too jittery, skittery and less directional. So I would like to reduce the pressure. But what to? When the previous vans came back from a service, they were always put back at the highest recommended, so I'd drop them back. At this moment, I do not know what they are set to, but the feel is that they are set to the max recommended, the van has been laid up for more than 6 months, I haven't been driving because of illness. So standing for that period of time, that's when you need CPs. But when I took it out for a short cross country (Somerset roads) trip when I was allowed to drive again a few days ago, I did not like the feel, but cannot decide if it is the CP sidewalls or just the high pressure. So I'll drop the pressure to see how they react. Any recommendations what to?
 
Sep 10, 2022
145
116
Warrington, UK
Funster No
91,229
MH
Elddis Majestic 125
Prior to my present van I always had a PVC. Sorry, woosh bang. The current one is a small 3.3 ton Elddis plastic bodied with CP tyres. The last PVC was originally fitted with CPs, but because of the harsh ride I lowered the pressures a little and moved over to standard tyres when they came up to replacement, still with reduced pressure. Às such they travelled well and comfortably. The ride was much better. Now, on this van, with the CPs, I truly dislike the ride. When I bought it, the tyres only had 5k on them, and were 15 inch on alloys with 215/70, shorter wheel base, higher wider plastic body and higher tyre pressure. So now, the ride is too jittery, skittery and less directional. So I would like to reduce the pressure. But what to? When the previous vans came back from a service, they were always put back at the highest recommended, so I'd drop them back. At this moment, I do not know what they are set to, but the feel is that they are set to the max recommended, the van has been laid up for more than 6 months, I haven't been driving because of illness. So standing for that period of time, that's when you need CPs. But when I took it out for a short cross country (Somerset roads) trip when I was allowed to drive again a few days ago, I did not like the feel, but cannot decide if it is the CP sidewalls or just the high pressure. So I'll drop the pressure to see how they react. Any recommendations what to?
I have an Elddis Majestic 125 with same 3300kgs and I don’t like the ride at all on the 215/70/15 CP tyres, it never feels fully under control at the front in my opinion. The tyres are at 80psi all round so I’m going to a weigh-bridge to check axle weights next week. I suspect I can lower the fronts to maybe 65psi but I think the rears will need to stay at 80psi. Biggest issue for me is that the TPMS (tyre pressure monitors) will show a fault (Peugeot Boxer) when I drop the front pressures and you can’t reset it to the new pressure and that will drive me mad.

if you are on CP tyres then the manufacturers will say 80 all round to stop flex in the sidewall but that’s why I’m going to a weigh bridge to see what weigh is on each axle When loaded for travel. My tyres are rated 109/107 which with a rear axle plated weight of 1900kgs means there is not much leeway on the 80psi. The front plated weight is 1750kgs so once I have been on the weigh Bridge I can see what the pressures could be reduced to.
 
Last edited:
OP
OP
Dorwyn
Aug 19, 2013
3,001
4,332
Wells, Somerset
Funster No
27,611
MH
Elddis 115
Exp
since 2004
I didn't realise that would be an issue. I too have a Pug, circa 2020. Presumably that system assumes CP, what would happen if you change to non CP?
 
Apr 20, 2020
1,094
2,410
Northern Ireland.
Funster No
70,057
MH
Adria Compact SC.
Exp
Since 2017
Get it weighed fully loaded and then email the tyre manufacturer with the axle loads and they may give you the correct pressure. I say “may” as Michelin will always say 80 psi in the rear but Continental will give you a lower pressure for the front and rear. I unfortunately have Michelins but run them at 55psi front and 70psi rear. The tpms on a Peugeot can be adjusted by a Peugeot dealer but some are reluctant to do so. I previously had two Peugeot based motorhomes and had both of them adjusted.
 
Oct 28, 2022
445
905
Funster No
92,132
MH
Rapido
I weighed mine a few weeks ago, it came out at close to 3400, so with a few more bits to add (45kg wolf and his food supply!) bikes, full tanks etc it will be around 3700 on initial deployment…..

so i worked out that the TPs would be 75 psi rears, 65psi fronts….these are for Michelin Agelis CP tyres…

since I haven’t ventured out since, i have not adjusted the TPs as understand higher pressure is better for sidewalls whilst standing…..

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Aug 9, 2020
437
660
Funster No
74,151
MH
Wildax
Exp
~20 years
Get it weighed fully loaded and then email the tyre manufacturer with the axle loads and they may give you the correct pressure. I say “may” as Michelin will always say 80 psi in the rear but Continental will give you a lower pressure for the front and rear. I unfortunately have Michelins but run them at 55psi front and 70psi rear. The tpms on a Peugeot can be adjusted by a Peugeot dealer but some are reluctant to do so. I previously had two Peugeot based motorhomes and had both of them adjusted.
The TPMS pressure thresholds can also be set using multiecuscan (it can do most of the peugeot/citroen modules, except engine/gearbox)
 
Oct 9, 2019
5,015
17,560
Todmorden
Funster No
65,104
MH
Van conversion
Exp
FUNSTER in a PVC
This conversation happens probably 6 times a year. Ignore the 80psi and contact the tyre manufacturer with your axle weights, if you haven’t been to a weighbridge go asap. You will probably find your pressure will be between 50 and 60 PSI which will be much less bone jarring 👏👏👏👍🏻👍🏻👍🏻
 
Apr 20, 2020
1,094
2,410
Northern Ireland.
Funster No
70,057
MH
Adria Compact SC.
Exp
Since 2017
Ignore the 80psi and contact the tyre manufacturer with your axle weights
Problem is that if you have Michelins fitted they will always say 80psi in rear. What I don’t understand is that the load rating on my tyres of 116 appears to be at 475 kpa which is 69psi. If the load rating is achieved at 69psi, why would you ever need to go higher than that?

55F205F0-CBD4-49B5-8962-5BBA99E56B83.jpeg

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Sep 28, 2015
2,071
2,675
Kingston upon Hull, East Yorkshire.
Funster No
38,946
MH
Hymer B544
Exp
2001 Caravans 2011 Motorhomes
Michelin CP tyres are designed to run at those high pressures, which is why I won’t have them. Running them at lower pressures will result in increased side wall flex which they aren’t designed to cope with, resulting in side wall cracking which contributes to side wall blow out.
My opinion, if you have CP tyres run them at the stupid pressures recommended and get rid asap, replacing them with decent C rated tyres from a manufacturer that will help you regarding axle loads/pressures. I chose Continental 4Season, plenty of others recommended on here.
 
Last edited:
Oct 9, 2019
5,015
17,560
Todmorden
Funster No
65,104
MH
Van conversion
Exp
FUNSTER in a PVC
Problem is that if you have Michelins fitted they will always say 80psi in rear. What I don’t understand is that the load rating on my tyres of 116 appears to be at 475 kpa which is 69psi. If the load rating is achieved at 69psi, why would you ever need to go higher than that?

View attachment 729215
Drop your pressures to 69 then and see why they run then, I have Never had any luck with Michelin’s not one has got passed 15,000 without either wall cracking or attracting a screw or nail 🤪 Contis on the other hand 38,000 miles on replacement with no wall cracking at all.
 

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