Tyre Pressures
Discussion
Hi,
I have recently been pondering over tyre pressures and how much it effects the characteristics of the car after blindly changing mines.
The first time I went to 'check' my tyre pressures on my Fiesta ST, I went and set the machine at 33psi and set all four tyres at that, just like I used to with my last car which also had 17" wheels. However I never checked what the were at originally or thought much about what they should be set at...
I noticed instantly when driving that there was change, a change for the worse. The car seemed to to more frantic than before, and I am speaking about driving in a straight line at 30mph! At 60mph and above the car was extremely busy and skippy, especially at the rear. It was actually quite difficult to drive the car quickly, whilst feeling like I had full control. The back end seemed to have a mind of its own and now slight lift off oversteer seemed to begin to happen at much lower speeds. But again this was more of a bumpy non-linear feeling way.
I checked the manufacturers ideal pressures; 36psi front and 26psi rear for unladen below 190kph.
After reverting back to these pressures the car handles and rides a lot better and is predictable unlike before. In future I'll be paying more attention to what the pressures actually should be.
How often do you check pressures and do you follow what the manufacturers suggest?
I have recently been pondering over tyre pressures and how much it effects the characteristics of the car after blindly changing mines.
The first time I went to 'check' my tyre pressures on my Fiesta ST, I went and set the machine at 33psi and set all four tyres at that, just like I used to with my last car which also had 17" wheels. However I never checked what the were at originally or thought much about what they should be set at...
I noticed instantly when driving that there was change, a change for the worse. The car seemed to to more frantic than before, and I am speaking about driving in a straight line at 30mph! At 60mph and above the car was extremely busy and skippy, especially at the rear. It was actually quite difficult to drive the car quickly, whilst feeling like I had full control. The back end seemed to have a mind of its own and now slight lift off oversteer seemed to begin to happen at much lower speeds. But again this was more of a bumpy non-linear feeling way.
I checked the manufacturers ideal pressures; 36psi front and 26psi rear for unladen below 190kph.
After reverting back to these pressures the car handles and rides a lot better and is predictable unlike before. In future I'll be paying more attention to what the pressures actually should be.
How often do you check pressures and do you follow what the manufacturers suggest?
neil1jnr said:
Hi,
I have recently been pondering over tyre pressures and how much it effects the characteristics of the car after blindly changing mines.
The first time I went to 'check' my tyre pressures on my Fiesta ST, I went and set the machine at 33psi and set all four tyres at that, just like I used to with my last car which also had 17" wheels.
Curiosity begs this question: Why did you think tyre pressure was linked to rim diameter?I have recently been pondering over tyre pressures and how much it effects the characteristics of the car after blindly changing mines.
The first time I went to 'check' my tyre pressures on my Fiesta ST, I went and set the machine at 33psi and set all four tyres at that, just like I used to with my last car which also had 17" wheels.
It's an odd thing. I set mine to 30 psi, as that is what the book says. But I checked my pressures the toher day and they were at 32 psi, and i didnt really notice much.
However, on my bike, I can feel when the pressure drops a few psi, or conversly if its gone up a few (changes in ambient temp)
However, on my bike, I can feel when the pressure drops a few psi, or conversly if its gone up a few (changes in ambient temp)
speedking31 said:
Uneven wear is a sign. Overinflated tyres wear the middle of the tread while underinflated wear the edges. Adjust pressures until wear is even across the width of the tyre.
There are worse rules, but I wouldn't be setting tyre pressures by wear rates. Set them to the manufacturers figures.doogz said:
neil1jnr said:
The car doesn't understeer at all, it just feels right at those pressures.
I don't doubt it's fun to drive, my comment was a bit tongue in cheek, but I don't believe it doesn't understeer at all, not in standard guise.I can imagine it would near the limits.
If the front tyres were down to 26psi I think it would probably understeer more easily, just like it almost constantly wanting to skip into oversteer with over inflated rears.
Kawasicki said:
speedking31 said:
Uneven wear is a sign. Overinflated tyres wear the middle of the tread while underinflated wear the edges. Adjust pressures until wear is even across the width of the tyre.
There are worse rules, but I wouldn't be setting tyre pressures by wear rates. Set them to the manufacturers figures.I have been running mine at 35-37PSI, Book says 32, which they are set at right now, as I had to have a new valve put in one tyre and they told me they sent to work experience lad round setting them all to 32 for me.
Will probably be upping them again, just they look a bit low on 32.
Will probably be upping them again, just they look a bit low on 32.
LordHaveMurci said:
Run my 996 at 10-12% lower than handbook recommends, the Clio is whatever I set them at really. The Clio has a slow puncture in the NSR, when I forget to top it up it is noticeable when driving it.
When the Clio is running on R888's they are set much lower.
Hot or cold?When the Clio is running on R888's they are set much lower.
Big difference.
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