Registered to this forum to give my comment.
wont introduce myself in a seperate topic , because only medle in topics with tire-pressure.
In 2008 I got hold of the formula that the European tyre-makers use to determine the advice-pressures. Learned myself Excell to make spreadsheets for it, once I declared the formula holy.
Translated a few from Dutch to English to go worldwide with it, and discovered that way the different calculation in America and Europe.
I am not a tire-specialist ( profesion is Optician) but got much wiser surfing the internet and bothering people who knew more about it, capri racer is one of them.
Came to some conclusions , from wich I had to come back at, but think I figured it out now.
Placed a lot of spreadsheets and found articles on my public map of skydrive that belongs to my hotmail adress with the same username as here.
My public map with a lot of English between the Dutch
But nou my imput here.
In Europe before 2000 there was always given a pressure-advice for normal use, and that was for 3 persons and a little load, and gave front higher pressure then behind for frontwheeldrive ( always motor in front so front heaviër) and that are probably the cars you read those pressures from.
After 2000 this advice is not given anymore, normal use is now for 4 persons and load.
For that the GAWR's are filled in the formula. GAWR rear is mostly higher then front so for that reason behind higher pressure. Some smaller cars have a higher GAWR ( Gross Axle Weight Rating) front then behind and there you see old full loaded and new normal advice front higher then behind.
Tire-pressure advice is all about Load on the tire, a bit about speed, and even less about camber angle ( alignment wheels like this on the axle /-\ instead of |-|).
Car makers dont care about over or under-steer, the only thing that interests them is that the tires dont get damaged by the 10 to 20 times deflecting and flexing of every point around the tire, and then especially the sidewalls.
By the Ford/Firestone-affaire they realized that some tires may deflect less then the average tire and so should have lower maximum load then they had always calculated.
So to prefent law suts they overreacted by advising pretty high pressures for every tire.
Also the formula was not adequate in America, but only as late as 2005 American TRA swiched over to the European formula ( ETRTO) wich proved to be save for standard load and XL/reinforced/Extraload tires, but only for P-tires and XL, why not also for C-load and up for wich still to low pressure advice for lower loads.
Enaugh for now , but to be continued if wanted.
wont introduce myself in a seperate topic , because only medle in topics with tire-pressure.
In 2008 I got hold of the formula that the European tyre-makers use to determine the advice-pressures. Learned myself Excell to make spreadsheets for it, once I declared the formula holy.
Translated a few from Dutch to English to go worldwide with it, and discovered that way the different calculation in America and Europe.
I am not a tire-specialist ( profesion is Optician) but got much wiser surfing the internet and bothering people who knew more about it, capri racer is one of them.
Came to some conclusions , from wich I had to come back at, but think I figured it out now.
Placed a lot of spreadsheets and found articles on my public map of skydrive that belongs to my hotmail adress with the same username as here.
My public map with a lot of English between the Dutch
But nou my imput here.
In Europe before 2000 there was always given a pressure-advice for normal use, and that was for 3 persons and a little load, and gave front higher pressure then behind for frontwheeldrive ( always motor in front so front heaviër) and that are probably the cars you read those pressures from.
After 2000 this advice is not given anymore, normal use is now for 4 persons and load.
For that the GAWR's are filled in the formula. GAWR rear is mostly higher then front so for that reason behind higher pressure. Some smaller cars have a higher GAWR ( Gross Axle Weight Rating) front then behind and there you see old full loaded and new normal advice front higher then behind.
Tire-pressure advice is all about Load on the tire, a bit about speed, and even less about camber angle ( alignment wheels like this on the axle /-\ instead of |-|).
Car makers dont care about over or under-steer, the only thing that interests them is that the tires dont get damaged by the 10 to 20 times deflecting and flexing of every point around the tire, and then especially the sidewalls.
By the Ford/Firestone-affaire they realized that some tires may deflect less then the average tire and so should have lower maximum load then they had always calculated.
So to prefent law suts they overreacted by advising pretty high pressures for every tire.
Also the formula was not adequate in America, but only as late as 2005 American TRA swiched over to the European formula ( ETRTO) wich proved to be save for standard load and XL/reinforced/Extraload tires, but only for P-tires and XL, why not also for C-load and up for wich still to low pressure advice for lower loads.
Enaugh for now , but to be continued if wanted.
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