Tyre Pressure

[Global_Warmer]

I also run 40 psi all round in 255/35/17s.

If I know I'm going to be smashing it, 50 will be what I run.

Will say though, that my car isn't a daily, already has rock hard suspension and no rear seats

Must handle like a dog on tiles.

[Ten Four]

Handles like a go kart on the track.

Or a rabbit on the road (jumps around).

[Global_Warmer]

50psi would be absoluley shithouse for handling!!. You need some degree of flex in the sidewall to allow the tyre to do its job and get traction.

Watch the video from 40sec mark.

[Ten Four]

Thats a slick & I cbf explaining.

Car handles insane right now and I'm not changing it.

[PN-Mad]

OK, its basics but in case anyone has overlooked it -

You set your pressures when the tyre is cold. when you drive the tyre gets hot and pressure increases.

Read it like this - your a dead set idiot if your tyre says max 50psi on the sidewall, and you go pump it up to 50psi when its stone cold. When it gets hot- it'll add much more pressure leading to potentially unsafe situations.

Thats why "Global Warmer" had a better experience on putty rd, when he lowered his pressures, because it wasn't causing his tyres to over pressurise when hot.

Sorry if you know all this and I have wasted your life.

[WGNPWR]

pV = nRT

[ironpaw]

How long does.it take to warm up the tyres? Cos it takes me about 5 to 10 min to get to a servo...

[Old Gregg]

OK, its basics but in case anyone has overlooked it -

You set your pressures when the tyre is cold. when you drive the tyre gets hot and pressure increases.

Read it like this - your a dead set idiot if your tyre says max 50psi on the sidewall, and you go pump it up to 50psi when its stone cold. When it gets hot- it'll add much more pressure leading to potentially unsafe situations.

Thats why "Global Warmer" had a better experience on putty rd, when he lowered his pressures, because it wasn't causing his tyres to over pressurise when hot.

Sorry if you know all this and I have wasted your life.

Wouldn't the pressure ratings on the tyres be cold values taking into account any increase due to heat build up? ie 50psi max means 50psi max when cold.

WGNPWR - Wouldn' Charles' law be a better one to throw in there?

[jidge]

Has anyone ran nitrogen in their tyres?

[WGNPWR]

WGNPWR - Wouldn' Charles' law be a better one to throw in there?

hehe

same thing, different way of writing it

plus i used that equation about 5 min before i wrote that post

[zei20l]

Has anyone ran nitrogen in their tyres?

no, but i believe the GTR uses it. for those that dont know, nitrogen isnt affected as much (if at all) by heat caused by friction/brakes/etc

[bigkevracer]

How long does.it take to warm up the tyres? Cos it takes me about 5 to 10 min to get to a servo...

Depends if you swerve violently racing style

[Old Gregg]

hehe

same thing, different way of writing it

plus i used that equation about 5 min before i wrote that post

Glad you are doing the Chem homework I set you in class today.

[WGNPWR]

Glad you are doing the Chem homework I set you in class today.

so happy its not chem

more like fluid dynamics

[Brandon]

OK, its basics but in case anyone has overlooked it -

You set your pressures when the tyre is cold. when you drive the tyre gets hot and pressure increases.

Read it like this - your a dead set idiot if your tyre says max 50psi on the sidewall, and you go pump it up to 50psi when its stone cold. When it gets hot- it'll add much more pressure leading to potentially unsafe situations.

Thats why "Global Warmer" had a better experience on putty rd, when he lowered his pressures, because it wasn't causing his tyres to over pressurise when hot.

Sorry if you know all this and I have wasted your life.

Very true. Once I check the pressure after driving from Brisbane to Gold Coast on a hot day and its showing 58 (was 40 at cold)! I got a shock of my life and immediately reduce it. I normally set mine to 38 (cold) these days and around 34 (cold) for some spirited driving.

[zei20l]

how about measure the pressure before you leave home. if they are down 4psi each, then go put 6 or 8psi in at the servo.

drive around normally. check them again the next morning when cold, then release any excess pressure.

easy!

[bubba]

You must have good suspension to compensate your tyres which are as hard as concrete!!

Must be bloody slippery in the wet/rain with those pressures.

Tein super wagons, 33gtr front swaybar.

And no, it's actually got a fair bit of grip in the wet even in 2WD.

Edited April 8, 2011 by bubba

[910trx]

36 psi cold for 17 inch wheels, but every tyre is different

higher pressures, better response

lower pressures better grio

but this does not mean that 22 psi handles better than 36psi thats just stoopid - thought i'd throw that in just incase someone tries it...

also i have about 75% of my tyre filled with nitrogen from the servo

[ironpaw]

Nitrogen doesn't do jack unless you're tracking it...

http://www.straightdope.com/columns/read/2694/is-it-better-to-fill-your-tires-with-nitrogen-instead-of-air

[RS4-S]

41 psi on 235/40R18. was running 36psi and it cornered like shit with abit of understeer. much less understeer and 'IM ON A BOAT' feel.

as for nitrogen.

1- much less moisture in your rims/tyres.

2 - psi doesnt get higher with tyre temp (more stable pressure).

3 - pure nitrogen is more dense than compressed air, so less frequent pressure top ups at the servo. (perfect for trailer tyres)