Tyre pressure help
Discussion
By my very rough reckoning, a tyre with no load would need about 20psi.
Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at thrice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at thrice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
Edited by Pica-Pica on Friday 4th April 21:20
Pica-Pica said:
By my very rough reckoning, a tyre with no load would need about 20psi.
Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at trice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
Thrice. A trice is a very short time, an instant really.Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at trice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
HTH!
Maxym said:
Pica-Pica said:
By my very rough reckoning, a tyre with no load would need about 20psi.
Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at trice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
Thrice. A trice is a very short time, an instant really.Now my Fabia at 1300kg needs 32psi (at twice your car’s weight)
My 335d at 1750kg needs 38 psi (at trice your car’s weight)
So 24 to 26 psi would be about right.
If it were me, I would use 26psi for the MOT, then afterwards (and rectifying any issues) research with some tyre makers what tyres to use and they would advise on the pressure.
HTH!
There is no formula, far too many factors affect it.
The way to do it is with a chalk test where you draw a thick line across part of the thread, drive in a straight line, then see if the chalk mark has worn evenly. If the edges are whiter than the middle then it's over inflated, if the middle is whiter then it's under inflated.
The way to do it is with a chalk test where you draw a thick line across part of the thread, drive in a straight line, then see if the chalk mark has worn evenly. If the edges are whiter than the middle then it's over inflated, if the middle is whiter then it's under inflated.
Yes there is a formula for that, wich this " pigheaded Dutch selfdeclared tyrepressure- specialist got hold of end 2007, but lineair calculation is not that bad.
The official european formula next.
Needed pressure=( real load on tyre/ maxload of tyre)^1.25 x referencepressure .
Or the other way around as lists are made next.
Loadcapacity =( actual pressure/ referencepressure/) ^0.8 x maxload.
That ^X is a power , like ^2 is square, and ^0.5is root, on sciencetific calculators there is a button X^y for that.
In the beginning of my tyrepressure calculation story ( began end 2007) I once calculated it for a Westfield with 400 kg max axleloadcapacity.
I then used wrongly the higher maxcold pressure of 3.5 bar instead of the 2.5 bar referencepressure, and came to 1.4 bar.
So if rightly calculated , it would even come lower.
I can make a cold pressure/ axleloadcapacity- list for your tyre, so you can look back the expected axleloads in that .
With builded in maximum reserve at wich comfort and gripp still acceptable. In that I use an even tighter formula, closer to lineair calc. Lineair calc is same as using power ^ 1 in both formula's.
But problem shal be that your old tyres dont give the needed information on sidewall.
If you can find them, search for next.
1 . Maximum load or loadindex( introduced round 1974)
2. Kind of tyre to determine referencepressure.
3, speedcode , less important , to determine for wich speed maxload is given.
Give it here, and I will make a list.
You can experiënce some discomfort the first 15 minutes of driving.
This because of flattened treath on the ground.At a healty tyre this dissapears itself by driving.
And its yust how the car was stored, if tyres lost their quality.
Tyres covered for UV ( sun) light by storing inside.
And not close to electric devices that produce Ozon as sideproduct.
The official european formula next.
Needed pressure=( real load on tyre/ maxload of tyre)^1.25 x referencepressure .
Or the other way around as lists are made next.
Loadcapacity =( actual pressure/ referencepressure/) ^0.8 x maxload.
That ^X is a power , like ^2 is square, and ^0.5is root, on sciencetific calculators there is a button X^y for that.
In the beginning of my tyrepressure calculation story ( began end 2007) I once calculated it for a Westfield with 400 kg max axleloadcapacity.
I then used wrongly the higher maxcold pressure of 3.5 bar instead of the 2.5 bar referencepressure, and came to 1.4 bar.
So if rightly calculated , it would even come lower.
I can make a cold pressure/ axleloadcapacity- list for your tyre, so you can look back the expected axleloads in that .
With builded in maximum reserve at wich comfort and gripp still acceptable. In that I use an even tighter formula, closer to lineair calc. Lineair calc is same as using power ^ 1 in both formula's.
But problem shal be that your old tyres dont give the needed information on sidewall.
If you can find them, search for next.
1 . Maximum load or loadindex( introduced round 1974)
2. Kind of tyre to determine referencepressure.
3, speedcode , less important , to determine for wich speed maxload is given.
Give it here, and I will make a list.
You can experiënce some discomfort the first 15 minutes of driving.
This because of flattened treath on the ground.At a healty tyre this dissapears itself by driving.
And its yust how the car was stored, if tyres lost their quality.
Tyres covered for UV ( sun) light by storing inside.
And not close to electric devices that produce Ozon as sideproduct.
Edited by Jadatis on Saturday 5th April 11:06
Edited by Jadatis on Saturday 5th April 11:24
e-honda said:
If it is just to get to the mot it doesn't really matter as long as it is under the max psi for the tyre which is probably about double what the optimal pressure would be
Not necessarily. My wife’s car has 51 psi as maximum, and the optimum is 32 psi.As regards the MOT, I believe OP knows the tyres will need to be changed, but wants to find out if there is anything else major before spending out.
Jadatis said:
In the beginning of my tyrepressure calculation story ( began end 2007) I once calculated it for a Westfield with 400 kg max axleloadcapacity.
I then used wrongly the higher maxcold pressure of 3.5 bar instead of the 2.5 bar referencepressure, and came to 1.4 bar.
So if rightly calculated , it would even come lower.
I can make a cold pressure/ axleloadcapacity- list for your tyre, so you can look back the expected axleloads in that .
With builded in maximum reserve atcwich comfort and gripp still acceptable.
But problem shal be that your old tyres dont give the needed information on sidewall.
If you can find them, search for next.
1 . Maximum load or loadindex( introduced round 1974)
2. Kind of tyre to determine referencepressure.
3, speedcode , less important , to determine for wich speed maxload is given.
Give it here, and I will make a list.
Thank you. I will see what I can find outI then used wrongly the higher maxcold pressure of 3.5 bar instead of the 2.5 bar referencepressure, and came to 1.4 bar.
So if rightly calculated , it would even come lower.
I can make a cold pressure/ axleloadcapacity- list for your tyre, so you can look back the expected axleloads in that .
With builded in maximum reserve atcwich comfort and gripp still acceptable.
But problem shal be that your old tyres dont give the needed information on sidewall.
If you can find them, search for next.
1 . Maximum load or loadindex( introduced round 1974)
2. Kind of tyre to determine referencepressure.
3, speedcode , less important , to determine for wich speed maxload is given.
Give it here, and I will make a list.
Pica-Pica said:
Not necessarily. My wife’s car has 51 psi as maximum, and the optimum is 32 psi.
As regards the MOT, I believe OP knows the tyres will need to be changed, but wants to find out if there is anything else major before spending out.
Absolutly. As regards the MOT, I believe OP knows the tyres will need to be changed, but wants to find out if there is anything else major before spending out.
And yes, it failed or was abandoned due to rear brake efficiency. I now have to work out what the rear brakes are and probably replace the pistons. ( Drum )
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