Oversteer/understeer Tyre pressure query
Discussion
Good Day Guy's.
I have some articles from 1987 by BF GOODRICH tyres referring to how to balance oversteer and understeer mainly for track work. [Plus suspension and handling etc articles from a 'Fast Car mag circa 1986!!]
This I have followed since.
However I noticed recently that various bits of editorial comments and information lately in the magazines states the opposite including the bit on Autocars Arial Atom at the Pageant of power last week.
Briefly :- My article states, generalising.
To reduce Understeer raise pressures at the front and decrease at the rear.
To reduce Oversteer raise pressures at the rear and reduce at the front.
The articles in the mag are suggesting that now the opposite is true.
[That is lowering the pressure increases the tyre footprint and therefore grip. Increasing them 'decreases' the tyre footprint and decreases the grip]
I would be very pleased for some helpful comments. Thank you.
I have contacted Tyre companies before re this and they have done the Health and safety line with use only the rec pressures as stated by the manufacturer etc. That is fine but does not help my understanding.
Cheers
Safe Driving! ANDY
I have some articles from 1987 by BF GOODRICH tyres referring to how to balance oversteer and understeer mainly for track work. [Plus suspension and handling etc articles from a 'Fast Car mag circa 1986!!]
This I have followed since.
However I noticed recently that various bits of editorial comments and information lately in the magazines states the opposite including the bit on Autocars Arial Atom at the Pageant of power last week.
Briefly :- My article states, generalising.
To reduce Understeer raise pressures at the front and decrease at the rear.
To reduce Oversteer raise pressures at the rear and reduce at the front.
The articles in the mag are suggesting that now the opposite is true.
[That is lowering the pressure increases the tyre footprint and therefore grip. Increasing them 'decreases' the tyre footprint and decreases the grip]
I would be very pleased for some helpful comments. Thank you.
I have contacted Tyre companies before re this and they have done the Health and safety line with use only the rec pressures as stated by the manufacturer etc. That is fine but does not help my understanding.
Cheers
Safe Driving! ANDY
You're probably finding that by decreasing the pressure in the rear, the sidewall becomes softer and you can feel the car move around a bit more.
That's not really oversteer though, as the tyre is still gripping, you're just getting a few degrees of attitude due to leaning on the softer sidewall.
To actually reduce the grip, pump the tyre up by 10psi over standard. The tyre is too hard and will bounce over the bumps, and you have also reduced the contact area.
That's not really oversteer though, as the tyre is still gripping, you're just getting a few degrees of attitude due to leaning on the softer sidewall.
To actually reduce the grip, pump the tyre up by 10psi over standard. The tyre is too hard and will bounce over the bumps, and you have also reduced the contact area.
Andrew POULTON said:
Briefly :- My article states, generalising.
To reduce Understeer raise pressures at the front and decrease at the rear.
To reduce Oversteer raise pressures at the rear and reduce at the front.
That's weird. I don't think I've ever heard it that way round.To reduce Understeer raise pressures at the front and decrease at the rear.
To reduce Oversteer raise pressures at the rear and reduce at the front.
As to what it does to tyre wear, feedback, wet/dry performance difference and breakaway characteristics, that may be more complicated, but as far as I'm aware - beyond a basic minimum to keep the tyre inflated - more pressure equals less grip.
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