Technical Tyre Pressures

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Technical Tyre Pressures

this will sound stupid but that PSI right?

I think it was decks that brought this info into the forum from the french fiatforum..he brings lots of info over from that one for us here..so yes I believe it to be correct..
 
I'd say yours are spot on and Coyotes is just a spot on the low side (y)

Having tyres at 37psi is very green but personally I'd feel a bid insecure generating a bit of 'g' on the curves :devil:

Just depends how you drive really and how you value good mpg.
 
Handbook gives 2.1 bar (30.5 PSI) normal & 2.3 Bar (33.5 PSI) fully laden for 205/55VR16's. Have found that 32 PSI (2.2 bar) - 33 PSI is good in terms of comfort / fuel economy / tyre wear on the JTD... bearing in mind that the wheels are 16vt Coupe Alloys :D
 
Yes; I tend to use the fully laden figure of 33/34psi on my 205/55/16's most of the time (y)

Bit of a harsh ride on the P7's mind you. Have been thinking of lowering the psi a bit but price if diesel puts me off :D
 
36/7 sounds a little high.

I have my standard steel wheels (195/65/15) at 33 front and 31 rear. The handbook says 29/30 all round but thats a little too low imo.

I may try putting a little more air in, to see if it evens out my front tyre wear.

A greater footprint (lower pressure) will give you better grip and also a softer ride.

To a degree, but once you get too low pressure, the sidewall will take most of the weight and the centre wont be taking much weight at all. So again there will be less of a footprint, as the centre of the tyre wont be pushed down onto the road as much.
 
36/7 sounds a little high.

I have my standard steel wheels (195/65/15) at 33 front and 31 rear. The handbook says 29/30 all round but thats a little too low imo.

I may try putting a little more air in, to see if it evens out my front tyre wear.



To a degree, but once you get too low pressure, the sidewall will take most of the weight and the centre wont be taking much weight at all. So again there will be less of a footprint, as the centre of the tyre wont be pushed down onto the road as much.

in the hand book the 215/40/18's are 37 front and 34 rear(y)

no problems with handling(y)
 
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To a degree, but once you get too low pressure, the sidewall will take most of the weight and the centre wont be taking much weight at all. So again there will be less of a footprint, as the centre of the tyre wont be pushed down onto the road as much.
You can't really argue with basic physics. As soon as you remove air from the tyre then the footprint must increase. If you're simply saying a greater load is taken by the outside of the footprint at lower pressures then fine :)

Obviously, there comes a point when the increased grip you get from low tyre pressures is negated and in any case it's a really bad idea to go outside tyre manufacturers recommendations (they should know):
  1. poor handling due to soft sidewall
  2. very high rolling resistance
  3. heavy & uneven tyre wear
Go the other way and raise the pressure too high then the footprint reduces to the point that the tyre loses optimum grip with the tarmac. Not an issue unless you like those windy curves ;)
 
I find it quite scary the number of cars you see around with obviously soft tyres with the sidewalls rubbed away as a result.

Tyres are things which need to be taken care of, checked often for cuts and damage and pressure - which should be run at or around recommended pressures.

I was nearly involved in a big accident on a motorway not so long ago, as a result of a driver not taking care of his tyres, and being numb enough not to realise he had a totally flat rear tyre at 90mph. That was the end of his car and crash barrier, along with a couple of passing cars too. I just narrowly avoided it, as it all happened a few metres infront of me.

So it pays to know your tyres are in their best condition, at all times! :)

You can't really argue with basic physics. As soon as you remove air from the tyre then the footprint must increase. If you're simply saying a greater load is taken by the outside of the footprint at lower pressures then fine :)

Obviously, there comes a point when the increased grip you get from low tyre pressures is negated and in any case it's a really bad idea to go outside tyre manufacturers recommendations (they should know):
  1. poor handling due to soft sidewall
  2. very high rolling resistance
  3. heavy & uneven tyre wear
Yes, i agree with you there.

You need to get a happy compromise dont you, too low and you will scrub off the edges in no time, more heat will be built up which increases the chance of a blow out, steering will be more vague, grip could also be effected as the tyre is rolling over onto its sidewall and its making extra drag.

Too much can cause a hard ride, wear to the centre of the tyre, more likely to damage an over inflated tyre front driving up/against curbs (although just as easy with underinflation), blow outs can also be common, as when the tyre heats up, it will be at an even greater pressure.

So all im saying, is tyres are not to be played with, they need care :D
 
i always prefer to run tyres harder, the old allys i had, 225/40/18"s were running 38-39psi and tread wear was perfect, these were 8j rims,,

the new alloys with new rubber seem to run best about 37psi all round,


blow outs scare me, and you're far more likely to have a blow out with an under inflated tyre than one running harder,
 
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i always prefer to run tyres harder, the old allys i had, 225/40/18"s were running 38-39psi and tread wear was perfect, these were 8j rims,,

the new alloys with new rubber seem to run best about 37psi all round,


blow outs scare me, and you're far more likely to have a blow out with an under inflated tyre than one running harder,

Indeed you are yes, plus if you do get a puncture a high pressure gives you a bit of leway before it starts causing a problem.

Id opt for over rather than underinflated as its safer, although the correct pressure is best obviously.

Ive upped my Stilos pressures today, to 35 front and 33 rear, so ill see how i get on!
 
For those of us with tyre pressure gauges that read in bars this thread is a little pointless unless somebody posts a conversion table:p.
 
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