New tyres - pressure?

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1726 posts

Uber Geek

#756536 6-Feb-2013 13:20

I've had tires up to 45psi...

However on my Accord they're 35. It should say on sidewall. I'd err on the side of higher anyway. Save a bit of gas and if you forget to check them often at least you'll save the tires a little from running too soft.

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rayonline

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#756853 7-Feb-2013 10:56

Was told 38 for NZ roads, can use 28 but they would wear faster.

timmmay

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#756874 7-Feb-2013 11:49

My Corolla says 32psi (or whatever unit) somewhere, but I run 34 for a firmer ride and slightly better handling.

Batman

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#756879 7-Feb-2013 12:02

there is an optimum. if the pressure is too high the tyre will bulge and surface area of contact with road will decrease causing lower traction and uneven/increased wear.

this optimum is different for every tyre and perhaps has little to do with the car apart from how much it weighs in the front relative to the back and hence the pressure will need to reflect this difference mainly for even car height front vs back.

handling is hard to predict unless you ask a formula 1 team to check it out and i presume there are some rules but it is hard to generalise

Batman

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#756881 7-Feb-2013 12:03

SO: don't go too high don't go too low and you'd be fine :)

but don't ask me how high is too high sorry i don't know

Goosey

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#756896 7-Feb-2013 12:57

36 seems to be the reccomendation from the guys who run the driver training courses at the local speedway circuits. I drive 36 in my euro and change it as required depending on my loads.

Depends on the tyres. Id say the petrol flap guide was meant for the factory fitted tyres under normal operating conditions.

TheUngeek

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#756914 7-Feb-2013 13:20

What kind of car is it? Size and weight matter with pressure.
Any thing over 1000-1200 kg should definitely be over 30psi.

Tyre pressure is all about making sure the contact patch is as big as possible whilst keeping the side wall tight

rayonline

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Uber Geek

#756997 7-Feb-2013 15:46

TheUngeek: What kind of car is it? Size and weight matter with pressure.
Any thing over 1000-1200 kg should definitely be over 30psi.

Tyre pressure is all about making sure the contact patch is as big as possible whilst keeping the side wall tight

Just a 2.0L VW Bora sedan 4dr.

Goosey

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#757001 7-Feb-2013 15:57

ahh I have a '99 NZ new Passat 4 door.
Im running on 16inch rims with semi directional tyres and the reccomended pressure is 35psi. The petrol flap says 32.

EDIT: Dont trust the service station guages and always check pressure when the tyre is cold.
( I used to run servo's and most in the industry were tired of continued damage to the 'free air' gear including theft so expenditure on the free air was limited and only when it got really bad / nicked). The public dont care about the free air gear and simply 'drop it on the ground', twist the hose, run over the hose etc etc.

rayonline

1730 posts

Uber Geek

#757009 7-Feb-2013 16:22

Seems about right then. It does feel firmer similar to the Corolla hire I had in Chch at Apex.
The ones before the tyres were all similar but the front left one had outer wearing more, the tyres were pretty newish I think off the auction it was an import but they just lasted 28,000km, mainly city driving, is that normal? Perrali P7s. I read that if you do more stops and starts and turns in the city, they wear off faster, not sure if the lower 28 pressure that I used contributed.

cyril7

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#757024 7-Feb-2013 16:55

Hi, am mate owns an independant tyre shop and has done for near on 25yrs, he also has a couple of race cars, rally and track.

At his recommendation for some years now I have operated the tyres on my XR6 at 36psi, and that seems to be the pressure you should be running modern lower profile tyres at. Lesser higher profile tyres should be in the 34 region.

His advise is what the tyre companies recommend for our course chip roads and the fact that modern tyres have more flexible walls than previous, so high 30's is pretty much normal.

Cyril

alasta

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#757175 7-Feb-2013 23:17

Gooseybhai: Dont trust the service station guages and always check pressure when the tyre is cold.
( I used to run servo's and most in the industry were tired of continued damage to the 'free air' gear including theft so expenditure on the free air was limited and only when it got really bad / nicked). The public dont care about the free air gear and simply 'drop it on the ground', twist the hose, run over the hose etc etc.

I've never understood why petrol stations don't just charge a small fee (e.g. $2 coin operated) for the use of the tyre inflation facility. My local Pak N Save Fuel got rid of theirs some time ago probably for the reasons you mentioned, but it's an essential service and I'd rather that they charge to cover its upkeep rather than not offer it at all.

Where else can you go to get your tyres inflated? I'm assuming a tyre shop would look at you funny and/or charge a huge fee for doing it.

richms

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#757180 7-Feb-2013 23:58

I thought they were required to provide the air by some arcane old law or something?

Richard rich.ms

DaveDog

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#757239 8-Feb-2013 10:02

Perhaps it is slightly off topic - but is this Nitrogen fill a waste of time or what?

scuwp

3764 posts

Uber Geek

#757277 8-Feb-2013 12:47

DaveDog: Perhaps it is slightly off topic - but is this Nitrogen fill a waste of time or what?

Depends who you talk to and/or what research you find. I am firmly in the 'no difference whatsoever - tyre shops just scalping more money" camp.

A quick google finds the following which sums up a big look I had on this topic last year

Unfortunately, these claims don’t stack up. Consumer Reports in the US conducted a year-long trial with nitrogen and found it only marginally reduced tyre-pressure loss. Even a nitrogen-filled tyre loses pressure, which means topping it up periodically – but topping it up with air will undo the "benefits" of the nitrogen already in there. So you'll need to pay for nitrogen top-ups from the tyre shop.

That nitrogen cools your tyres and extends tread-life is also tricky. Cooling down a tyre may give a little more tread life but can also reduce grip – not pleasant to discover when driving on a cold, wet road. Tread is not the only thing holding you on a wet road – the compound of the tyre, inflation pressure and heat in the tyre also play crucial roles.

The argument that nitrogen reduces moisture in the tyre is irrelevant as it’s extremely unlikely that your tyres or rims will fail because of moisture inside a tyre.
We say

Nitrogen provides some cost-benefit to heavy commercial vehicles and helps stop Formula 1 tyres from overheating. But for the average motorist it provides virtually no benefit, costs money, and may reduce safety rather than improve it. It’s a good way for tyre companies to make a little extra money though.
Regularly checking your tyre pressures and being gentle with your right foot are our advice for improving tyre life and fuel economy.

Never attribute to malice that which is adequately explained by stupidity - Robert J Hanlon

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