What PSI Your Tyres Are

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Originally Posted by EuroAccord13

The reason we run higher Psi on the tyres on the track or twisties is to strengthen the sidewalls due to the stress when doing hard cornering..

The general rule is to leave like a 25% window, say a tyre's maximum Psi load is 60Psi, the 25% window will be 45 - 60 Psi... So that 15 Psi range is where you will experiment and find out which Psi in that range will allow you to perform at it's best.. After that, you fine tune it to like 1-2 Psi range... Takes some work but heck, it's good for cars with no suspension mods!

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id have to disagree, you obviously dont want the tyre to be rolling/folding over during hard cornering, but once your above the tyre pressure that keeps the tyre in correct formation, adding more pressure isnt going to magicaly improve performance/grip of the tyre.

You will greatly reduce the area of the contact patch, which isnt worth the trade off for less sidewall flex, which isnt always a desirable thing in road racing anyways. You will also overwork the centre of the tyres tread.

Dont use some extremly poor rule of thumb, that seems to work against the recomended tyre pressures of most tyres, use the manurfactures actual info for the tyre.

ie, Toyo RA1

Air Pressures Recomendations:
Dry Conditions
Front Drive - Starting minimum 24 psi.
Rear Drive - Starting minimum 18 psi.
Goal - 41 to 43 psi (hot)
Wet: (heavy water layer)
Front Drive - Starting minimum 28-30 psi.
Rear Drive - Starting minimum 22-24 psi.

Front Drive - Starting minimum 18-20 psi.
Rear Drive - Starting minimum 12-14 psi.

To pump your tyres up to 45-60psi cold, and only play around in that range is crazy, track car or street car. If you want less sidewall flex use a tyre with stiffer sidewalls.

http://www.tirerack.com/about/techcenter.jsp the first 5 links are reguarding tyre pressures.

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Originally Posted by Muzz

id have to disagree, you obviously dont want the tyre to be rolling/folding over during hard cornering, but once your above the tyre pressure that keeps the tyre in correct formation, adding more pressure isnt going to magicaly improve performance/grip of the tyre.

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agreed
i personally go with 40psi cold
due to what i do with my car
at track it heats up to around ~46psi
i always make sure my chosen tyres have a max of 51

but thats just me
for people who just do daily driving
proba just have it slightly above the recommended psi

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Originally Posted by SiReal

higher pressure would mean less tyre to surface contact, hence not as effective for the wet. this runs along the same reason as to why draggers lower their psi before they run, so more rubber touches the ground.

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IMO - that is not entirely true. If you compared a pressure of 40psi against 20psi in the wet, 40psi would be far better. Lower pressure in the wet means the tyre has more tendency to aquaplain, a very dangerous situation in the wet.

Similarly, drag tyres are normally lower psi because they are after a soft side wall, hence why drag tyres don't tend to be low profile, soft side wall means better grip for the launch.

Anywhere between 32psi - 40psi cold should suit most cars/wheel combo's on this forum for street use, just your personal preference where you wanna be within that range, and remember to check cold.

Track days and semi's slicks are different of course.

Quote:

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Originally Posted by SiReal

higher pressure would mean less tyre to surface contact, hence not as effective for the wet. this runs along the same reason as to why draggers lower their psi before they run, so more rubber touches the ground.

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agree 100% with all your post except this bit.

in the wet, having less tyre contact (up to a point) is desirable.

less contact means more weight on that patch of tyre, which makes it harder to aquaplane. this is one of the reasons why wider tyres are not as good in the wet - large contact patch means less force per cm^2 of rubber, thus its easier for the water to get underneath.

a big reason why skinny tyres are better in the wet is because the water has less distance to travel before its out of the tyre, not so much the weight on the tyre.

i always adjust my pressures depending on what driving i'm doing..
195/50/15's

cold pressures
summer: 34F/36R
winter: 36F/38R
wet: 38F/38R

i prefer higher settings at rear as the front tyres heat up much quicker than rears so at hot operating temps the pressures equalize

ok I've read three pages of differeing opinions - all good.

What psi should I be running for 225/45 R17 Bridgestones on a factory Accord Euro Lux rim if I'm only doing daily driving and no track work etc. I stopped at a tyre place last night and they increased my tyre psi from 32 that I was running to 40. They said I was running too low. I just want good even tyre wear for daily driving. Any thoughts?
Cheers

36f 34r

How about for track, wat kind of pressures do people reccomend? On street i tend to run them all at 38.

im not sure, but id say lower for track

34f 32r, also depending on weather and track surface grip

coz wen ur tracking, theyll be that much more high speed and fast cornering that the tyre pressure should significantly increase after a few laps...

34f32r cold, should hit at least 40f38r after a few good hard laps

but im not sure, som1 else might have a different view

also, its about preference, some ppl feel their car handles better wen the tyres are on 40f 38r cold, and then it hits at least 48f 46r after a few hard laps

try both configurations, see how u feel....but i woodnt recommend running higher than 40f 38r cold wen goin to the track...

37 front 36 rear touge runs !! 15``

this kind of thread, u're likely to get some really vague answers.

tyre psi really depends on size, profiles and brands.

i have 5 sets of wheels, 5 different brands of tyres on each set, all sets running slightly different tyre pressure. :)

best way is to try it urself! everyone likes different kinda feel and handling.