Correct Tire pressure...

[Nephilim]

Me now on eagle f1s (thai) (205/45/17) and I pump 270kPa everytime. My logic is this:

 

1) Recommended pressure according to website - 36psi/250kPa

2) I only have time to pump at night at the end of long journey (+1.5psi/10kPa)

3) Estimated calibration error of digital air pump at Mobil (+1.5psi/10kPa) - haven't measure with gauge yet

 

My FC is good and after 6k km I dun see any noticeable treadwear in the center. When my tyres first left the workshop it was pumped to 200kPa and my FC was horrible.

 

My previous stock tyres was 175/60/16 (higher profile) and recommended was 220kPa so following same logic as above (+20kPa) I always pumped 240kPa. Never gave me prob as well for 20+k km.

[Icekitten]

Err...my car feels bumpy anyway coz of the coilovers. Guess I'll have to try pumping different pressures and notice if there's any difference.

 

But generally, with increase of tyre size and profile, there should be an increase in TP too rite? This is what I gather so far. So in which case the sticker can be ignored. Ya?

[Pisces69]

If u r able to monitor the wear & grip & comfort levels & all seem to b in order after some time, then u have got it right.

 

Stick to it.

 

Your original tyre of 175/60/16 seems like a very strange size. What car u driving?

[Pisces69]

Look at your tyres after about 10K km & pumping a consistence TP all that while & note how your tyre is wearing. If the wear is not un-even (ie. outside 2 edges or inside center line) then the pressure is suitable for that tyre.

 

The recommended TP is for the original size tyres which is not what u have now. Tyre shops sud b able to give u a guide but I notice they always like to pump up the TP quite hard.

[Nephilim]

Ya I know - whole Sin don't carry this size. If you recognize my avatar, it's a ractis

[Pisces69]

If you recognize my avatar, it's a ractis

=====================

 

Er.....Sorry for my ignorance, but what's a ractis?

[Nephilim]

Toyota Ractis - www.ractis.com

 

One of the best sellers in japan, one of the bottom sellers in singapore

[Pisces69]

Hmmmmm........Nice looking car. Looks abit like Jazz. The link is all in Japanese.

 

If the car is not common here, how u gonna get spares later on? U got some lobang?

[Nephilim]

It uses Vios' 1nz-fe engine and shares some common traits with Vitz/Yaris, and many Toyota models of the same range shares similar internal parts.

 

External/cosmetic parts a bit rare la, but I think my ride is unique enuff liao

 

Was actually thinking of getting Jazz till I saw this

- 1.5l

- semi-auto with paddle shifts

- cruise control

- very very big internal space for Jap hatchback (long wheelbase)

- FC around same as vios (so won't lose out too much)

- much nicer interior IMHO

- same price as Jazz + no need to pay KM's cut-throat servicing + insurance

 

Downside is of course parts rare and PI car lah.

[Pisces69]

So looks like u got a better speced model with all the bells & whistles. Much more fun then a Vios.

 

Only prob with PI cars is getting parts when it ages. Unless u ask the scrapyards to bring in for you, but it wil cost more then what they keep ex-stock.

 

If u sell it in a few years then u sud not have this problem but u also got to look at it's re-sale value then.

 

I did like the look of the Airwave (Jazz in wagon mode) but am curious how pple who buy from PI wil get their parts later on?

 

I was on the road today & saw the Colt. I thought it looks very similar to yours.

Edited February 13, 2007 by Pisces69

[Spikedoll]

[reply]

I know that. But some say you should have a lower tyre pressure for the front for better stability. So to have lower pressure in front or not?

I believe front (for front wheel drive) should be higher pressure, cos not enough pressure the tyre will flex and won't give better stability. Furthermore during hard cornering or emergency stopping, the weight of the car is transfered to the front wheel more, so sufficient pressure (hardness) is important to give better control of the vehicle.

 

this is what I thought too...but in earlier separate threads..I read rear should pump more pressure

 

now i always pump 230 front 220 rear

[Octopus]

this is what I thought too...but in earlier separate threads..I read rear should pump more pressure

I believe for rear driven vehicle, the rear tyre pressure is higher that front....

[Nothingtodo]

Me also pump average all round.. 210. too leh che to adjust pump pressure liao. Anyhow, the pump nowadays come with conversion between PSI and kpa at the push of the button.

[Nothingtodo]

For you bro:

 

http://www.thetyrepressuremonitor.com/safety.asp

 

 

Happy driving, and don't over inflat. Most tyres has their own recommended pressure. Keep to it as close as possible.

 

In Singapore, the whether is hotter, as such, during afternoon driving, your tyres will bloat more, due to air expansion. Adding to that the afternoon whether, the tyres becomes overinflated.

 

When attempting long drive up north, do not in any case attempt to overinflat otherwise your tyres will go fast and also decrease grip and increase danger.

 

Some tyre shops recommend Nitrogen to fill tyres because it expands less, do not easily escape.

[Nothingtodo]

Hi, u forgot that the air in the tyre expands when you drive. 35psi is very high

[Boyboy]

On the other hand I also hear that slightly underinflated tyres give better traction as there is more contact with the ground. Of course, if too much it just contributes to instability due to flexing of the sidewall.

 

Seems like there are two schools of thought regarding this. So which should be the appropriate way?

 

And is tyre pressure supp to remain the same even if you upsize your rims and tyres?

 

traction and stability are entirely independent.. so both are right..

[Octopus]

[reply]

For you bro:

 

http://www.thetyrepressuremonitor.com/safety.asp

 

 

Happy driving, and don't over inflat. Most tyres has their own recommended pressure. Keep to it as close as possible.

 

In Singapore, the whether is hotter, as such, during afternoon driving, your tyres will bloat more, due to air expansion. Adding to that the afternoon whether, the tyres becomes overinflated.

 

When attempting long drive up north, do not in any case attempt to overinflat otherwise your tyres will go fast and also decrease grip and increase danger.

 

Some tyre shops recommend Nitrogen to fill tyres because it expands less, do not easily escape.

 

 

From the link, seems like over-inflate by 110% is not as bad as under-inflate by 90%, in terms of braking performance vs air pressure...

[Nothingtodo]

Well, hv to also see the road type use for the test. So long don't overinflat too much, should hv minimum impact . If pump 200, an increase of 10 from the original, very minimum impact.