Self Inflating Tyres !!!!

[Gagakev]

Today is the third time on the trot I have checked my tyres both on the Van and the Truck and each time I have had to let them DOWN! Each time it is only a couple of Ilb's.
I know they say tyres should be checked when cold but with current temps what can you do?
I have used the same pressure gauge each time.

 

[Dustydog]

Now you know why F1 teams use tyre warmers / coolers.
Leave them alone

 

[WoodlandsCamper]

Summer has gone and winter is coming so the ambient temp is lowering. Come mid-winter's day you won't have any air left in the tyres at that rate.

 

[Gagakev]

Now you know why F1 teams use tyre warmers / coolers.
Leave them alone

So I am doing the wrong thing by checking them,

 

[Gagakev]

Summer has gone and winter is coming so the ambient temp is lowering. Come mid-winter's day you won't have any air left in the tyres at that rate.

Oh I will as I only have one more trip after this one

Will check them again when I am in the cold depths of Wales next week

 

[Dustydog]

Summer has gone and winter is coming so the ambient temp is lowering. Come mid-winter's day you won't have any air left in the tyres at that rate.

Oh I will as I only have one more trip after this one

Will check them again when I am in the cold depths of Wales next week

That's very good Kev. Can't get much lower.

 

[Sproket]

Kev

My TyrePal shows variations in the tyre pressure, truck front tyres this morning were showing 31psi ( normal pressure is 29 ) by the time i had got home from the van 36psi.... the ones on the van increase by over 10 psi in this weather ...... I just leave them .... :blink:
I'd be more concerned if they start to go down hmy:

 

[Jules_ht]

Kev

My TyrePal shows variations in the tyre pressure, truck front tyres this morning were showing 31psi ( normal pressure is 29 ) by the time i had got home from the van 36psi.... the ones on the van increase by over 10 psi in this weather ...... I just leave them .... :blink:
I'd be more concerned if they start to go down hmy:

I'm also a tyrepal user, although it was bought initially for track days where you expect/need a lot of heat and therefore a lot of pressure change (rises in tyre pressure when the vehicle is in use is due to the lower density of heated air).

The heat is coming predominantly from the flex in the tyre sidewall. If you're getting enough heat in the tyre to up the pressure by 10PSI I would suggest that you've got too much sidewall flex, which comes from running your pressures too low. Too much sidewall flex weakens the tyre and can result in blowouts at the extreme end of the scale. Suggest you review your cold pressures.

I use 39 rear on the car (and it rises to 41), and 40 on the van (which rises to no more than 43). Variations of a couple of PSI either way as a result of ambient temperature changes are to be expected, but provided the "rises when rolling" remain within the 10-15% kind of region it can be taken as reassurance that there is nothing to worry about.

 

[Sproket]

Jules

My tyres on the van when run at 58psi or 63psi can increase by nearly the same amount on a hot day by 10psi... I have been in touch with the technical bod's at Dunlop tyre's about it happening quite a few years ago when i purchased my first TyrePal unit, i was advised to increase the pressure upto 63psi and still the same thing happens hmy: .....

max tyre pressure = 65psi max load = 900kg per single tyre, Van MTPLM = 1600kg

65 / 900 = 0.07222
0.07222 x 1600 = 115.555
115.555 / 2 = 57.5 psi

I believe that a lot of heat from the tyres cant escape due to the van having a close fitting wheel arch with a motor mover fitted in front & mud flaps to the rear, as i have been watching this happen every time i have towed the van since 2011, i am not unduly worried about the increase in pressure i would be more bothered about a slow decrease as that will generate far more heat in the tyre and cause a blowout...
63psi + 15% = 72.45 or there about's = 10psi....

 

[Jules_ht]

I guess I must have subconsciously inferred from all the talk of c30PSI that we were talking a 25% increase although that is clearly not what you said. At c60PSI you're within the ranges commonly accepted as being OK as you say.

At 1600KG mtplm though, is it twin axle (which would imply lower pressures needed, since each tyre is not supporting half the van weight- not that I'm suggesting you do lower them)?

 

[Dustydog]

The school boys amongst you will remember Boyles and Charles Laws.
No wonder Kev had so many variations.
Check them on a cool early morning.