Tyre Pressures

[Paul Laing]

Anyone know what pressure these should be at on my car? Just checked them and some are 29.5 psi and others are 34 psi!!!!

I was thinking 35 or 36 all round the car? Or maybe 36 fronts and 35 rears? Something like that

Tyres are:

255/30/19 Pirelli P Zero Rosso's

275/30/19 Goodyear Eagle F1's

Any ideas? Cheers

Paul

[Bobbeh]

36 at front, 34 at back :)

[Terminator]

34 Front 32 rear for me.

Stock pressures are 36 all round

[michael]

Originally posted by Bobbeh
36 at front, 34 at back :)


Indeed, that's what the manual says - the factory label on the inside of my door suggests 36 all round and then kind of hints that this is when you have 4 people in the car.

[Paul Laing]

36 psi all round is for the stock 17s, not 19s though :)

Iv'e went with 35 front and 34 rear, will see how that goes for now :thumbs:

[Syed Shah]

Originally posted by Terminator
34 Front 32 rear for me.



This is what I run as well. A very good combo. :)

[AJI]

I find it depends what tyre your running, ie. width of tyre compared to width of alloys etc.
I simply fill my tyres up so that the full tread is in contact with the road. I've gone upto 38psi on the front with 245 width on aftermarket alloys and run 34psi on the rear with 285 on aftermarket alloys.
Be sure to note what the max. pressure is for your tyre and leave a good margin to allow for temperature differences etc.

[Vaughany]

On the NZ Site, it recommends 40psi all round, it says this is better for even tyre wear. Recommended psi of 36 supposely wears the middle of the tyre out before the edges.

I am running about 38psi all round on 19's, I thought this would be a happy medium, a little more air to help protect the wheels due to low profile tyres and terrible road conditions.

What do the Government spend our Road Tax on, definitely not the roads, expensive parties (meetings they call them) and refurbs for the Houses of Parlament.

I'm not bitter though!

[cg084]

Originally posted by mcanny
Indeed, that's what the manual says - the factory label on the inside of my door suggests 36 all round and then kind of hints that this is when you have 4 people in the car.


4 PEOPLE IN A SUPRA.........

Never really checked mine but the sticker is in Bars.

[geoffvalenti]

Originally posted by Vaughany
On the NZ Site, it recommends 40psi all round, it says this is better for even tyre wear. Recommended psi of 36 supposely wears the middle of the tyre out before the edges.


Well if 36psi wears the middle out first, 40psi will do it even quicker :(

You need to reduce the tyre pressures to wear the outsides more, but I wouldn't recommend the trial and error approach to getting the pressures right.

With stock rim and tyre sizes I'd go for the Toyota recommended pressures varying them in line with the manual, depending on the number of passengers (usually 1 at the most :)) and load carried. They didn't spend millions (of yen) on R&D for fun!

With non standard sizes I'd be inclined to speak to the tyre manufacturers for a recommendation of pressures

[Paul Laing]

two people recommending 34 front, 32 rear. Might give that a go, i put in 35 front and 34 rear and i kept thinking the tyres were going to blow!! Let alone 40psi

Paul :thumbs:

[Wez]

I run 36f and 34r and on a trackday may go up as high as 40 after a couple of laps to equal the pressures out.

:thumbs:

[Vaughany]

Alot of people take tyre pressures when the tyres are hot and cold as this shows an alteration in the tyre pressure. Just out of interest, am I right in saying when the tyre are warm, the tyre pressure is less (hot air, less dense) or is this the other way around.

Whichever way it is, if the manual states 36psi, is this pressure for when tyres are warm or cold.

[Syed Shah]

Cold is the standard way to check pressure in tires.

Hot air will have higher pressure as it has more energy, and so exerts more force on the tire walls.

[Vaughany]

Syed

Thanks for the info

[Soonto"HAS"soop]

Surely if the original stickers say 36 PSI all round with 4 people in the car, it would be better to run lower pressures when only 1 person is in the car? The 36 PSI relates to the weight of four people and the car, so surely with the lowered weight of only 1 or 2 people, the tyre pressures should be lower to accomodate the weight change.

Also when a tyre is driven for a period, the air inside increases in pressure dramatically. When I had 215/35/18's on my last car, the pressures could rise from 29 PSI to 38 PSI easily on a fair length run. starting at 40 PSI would therefore probably get to 50 PSI easily, this would then make the ride harsher and not pleasant.

Ben..

P.S. Before people ask how I know the pressures of my tyres, I had had a tyre pressure monitor system installed.

[SimonB]

I've posted this up before, but my original Jap handbook (for a facelift RZ) says 2.3 kg/cm2 all round, which is 33psi. I don't know why it should be different to everyone else's but I guess it is seeing as everyone else says 36psi is standard. Maybe the RZ is lighter?

http://www.simons-house.freeserve.co.uk/tirepressures.jpg

[AJI]

Got to remember that UK and some J-spec vary in weight quite a lot, that may be the case why some manuals will differ in normal running pressures.
36psi is stated as normal running pressure for stock tyres and rims. It says in the UK manual that if your carrying extra weight to increase the tyre pressure ie. long journeys with passengers etc.

But as you change rims and tyres they have an effect on how the tyre 'sits' on the ground. This also is the case if you raise or lower your car. Each tyre has a max pressure stating on the sidewalls so as long as your running with a good safety margin below this pressure you will be ok.
It seems to work well for me when I inflate tyres so that they 'look' right sitting on the ground. (I know that's not very technical but if you can see that you are wearing away rubber on the sidewall then you need more pressure etc. If you're wearing away the very middle tread alot faster than the outside then lower the pressure.
If you're running non-standard rims/tyres then it can only be a case of trial and error.

[lust2luv]

Originally posted by SimonB
http://www.simons-house.freeserve.co.uk/tirepressures.jpg

SZ-S?! :conf:

:looney: