Tyre pressures

[sagman]

What tyre pressures are you guys currently running?

 

[BenG]

28 PSI on the front and 30 PSI on the back...

A bit soft at first but once there warmed up there spot on.

 

[jonathanelwell]

I have 33 front and 30 rear. Works good for me.

 

[BenG]

28 PSI on the front and 30 PSI on the back...

I mean 30 front and 28 rear....Its been a long day !

 

[Cue]

i run 32/30

 

[Berty]

33 front 30 rear. Think that's what Renault say, works fine for me but not experimented at all

 

[Gordon]

Berty, you should try 32F and 30R, like Cue. It's a revelation from the standard Renault pressures. Transformed the way the car handled and removed loads of slow speed in town crashing and banging for me.

Not wanting to teach Grannie to suck eggs but everyone is checking tyre pressures with their own gauge before driving anywhere; not even half a mile to a garage. It's got to be done with a reliable gauge and when tyres are stone cold.

Not really worth doing otherwise. Temp gets into tyres fast and increases the pressures, not to mention garage tyre pressure gauges are notoriously patchy.

 

[BenG]

Ye I use a battery powered High pressure tyre inflator. I normally inflate them when there off the car too incase the weight of the car affects the reading. (not sure whether that will affect the reading tho)

 

[ravydavygravy]

Ye I use a battery powered High pressure tyre inflator. I normally inflate them when there off the car too incase the weight of the car affects the reading. (not sure whether that will affect the reading tho)

surely the weight of the car increases the pressure? Making yours too high.

 

[Stevie]

33 front 30 rear. Think that's what Renault say, works fine for me but not experimented at all

Me too, although can't say I notice any changes.

 

[George K]

My soft track tyres worked best at the recommedned pressures of 26/24. I tried 28/26 on the PE2 and certainly they had more grip when cold - for track days higher pressures are needed.

 

[BenG]

surely the weight of the car increases the pressure? Making yours too high

Thats why there set lower than what reno say.

 

[George K]

Basic physics (Boyles law) - Pressure will only change if volume of air in tyre changes significantly (which it does not for radials) or temperature changes.

 

[BenG]

Basic physics (Boyles law) - Pressure will only change if volume of air in tyre changes significantly (which it does not for radials) or temperature changes.

So it makes no difference whether the tyres are on or off ?

 

[George K]

Ben - that is correct. Load on the tyres will flex the sidewalls, but the volume inside and hence pressure will not change significantly - try squeezing a baloon full of water (not too hard!) - you will not change the pressure of the water, just the shape of the baloon

 

[Luke335]

Mmm, I didn't work very hard in physics but I'm not sure that theory works so well with air as it's much more compressable. Surely like putting weight on a spacehopper or an airbed increases the pressure, so would the weight of a car on the tyre (to a lesser extent)?

 

[hoolio]

PV=k

Your brain needs to be made of little bits of elastic to get your head around it but it is the law

 

[George K]

Only if the volume changes - Boyles law is Pressure x Volume = constant for a given temperature.

 

[tractor]

I'm doing a track evening at brands on monday and i'd like to make sure im running near-enough the right pressures.
At the mo i'm bunging-in 30 psi all round as cue suggests. I would do a few fast laps, come in and let them back down to that. But what really is the best pressure for a trackday?? George k suggests higher pressures are necessary, does anyone have any info on what pressures are best. i'm inclined to stick to 30/30 to start with.

Thanks in advance.

Dave

P.S. the weather reports are for a hot dry day 8)

 

[tractor]

Oh forgot to mention im running on nearly new PE2s.