New Tyres - What inflation pressure and why?

[peterljohnson55]

Hiya guys and gals,

Have just had new tyres fitted, but the 'technician' inflated them to 38 PSI. Recommended is 30 PSI.

He says the Ford and tyre geeks are wrong and he is right; his 38 will give more tyre life and a better ride.

Another person claims Ford/tyre manufacturers understate tyre pressure so as to generate sales.

So I am wondering ...
What tyre pressure(s) do you maintain and what is your rationale for that choice of pressure(s)?

(BTW, the newbies are Goodyear Assurance Fuel Max 215/60R16 95V, $146 each at Beaurepaires. I phoned and asked for price; was told $161, then asked for my NRMA 10% discount. Bit of a bargain, actually.)

[R1XSTA]

I keep my tires at 40psi. It increases wear but I believe gives you better ride.

[AUFanboy]

Higher pressure gives a firmer ride, better steering feel, and better fuel economy. I keep mine at 35 to 40 psi and find they wear evenly. If I run lower pressures the edges wear out first. Only downside is that the car can be a bit skitish over mid-corner bumps.

[Veefore]

BA XR6 and I run my 235/45-17's at 44psi. I found that any less than that and they always wear out on the edges.

At 44 the ride is a bit harsher but the tyres last a lot longer and actually give me more stability when pushing it a little.

Sent from my GT-I9300 using Tapatalk 2

[Marquis]

38 is good. I have 225 60 15s at 38 have done 45k+ and have heaps of tread left and very even ware

[Maka]

I run 38 psi allround for economy, steering feel & equal wear- trade off is bump absorption is a little harsher. Anyone know the 4psi rule & does it apply to only suv's/4wd's?

cheers, Maka

[Mr Hardware]

38, exactly why Maka said.

[Sox]

The tech is both right and wrong.

Correct pressures will make the tyres last longer, provide a more uniform contact patch on the road surface, run cooler, and make the car steer and handle better.
The correct pressure will generally be somewhat higher than Ford states.
He is wrong in that the ride will be worse, not better with higher pressures.

Ford have generally recommended tyres be run on the low side, it's understood this is to increase ride comfort for the masses.

I personally never have 36psi in all 4 tyres.
Depending on what I'm up to, I may have 40psi, or as high as 44psi or more.

Tyre pressures are dependent on 3 things, vehicle weight, tyre brand and size, and the way the vehicle is driven.

[4ford]

I run 17" wheels on my almost stock AU2 Fairmont 6, and have been running 38psi front and 36psi rear for the last 9 years, with excellent wear and ride.

I run slightly less in the rears since there is no load in the back of the car. In the unusual event that I have some load in the back/boot, I increase the rears to 38psi, if it's more that 'just down to the store and back'.

Oh, and those numbers are cool tyres, less than 3-4 kms from home.

[Maka]

Hi guys, when a tyre is inflated above recommended pressures, the sidewall becomes stiffer- its the sidewall that absorbs those little hits & shocks (road irregularities)- so higher the tyre pressure, harsher the ride on anything else but billiard table smooth roads. Just done a quick google (higher tyre pressures harsher ride)-

http://www.hankooktyre.com.au/Serv/I...m=3&ChildNum=3

cheers, Maka

[Maka]

Originally Posted by Sox

The tech is both right and wrong.

Correct pressures will make the tyres last longer, provide a more uniform contact patch on the road surface, run cooler, and make the car steer and handle better.
The correct pressure will generally be somewhat higher than Ford states.
He is wrong in that the ride will be worse, not better with higher pressures.
Ford have generally recommended tyres be run on the low side, it's understood this is to increase ride comfort for the masses.I personally never have 36psi in all 4 tyres.
Depending on what I'm up to, I may have 40psi, or as high as 44psi or more.

Tyre pressures are dependent on 3 things, vehicle weight, tyre brand and size, and the way the vehicle is driven.

Sox, sorry i couldnt help myself, thanks for agreeing....indirectly

cheers, Maka

[Sox]

Originally Posted by Maka

Sox, sorry i couldnt help myself, thanks for agreeing....indirectly

cheers, Maka

I totally agree with you, my sentenced wasn't phrased so well.

I said...
He is wrong in that the ride will be worse, not better with higher pressures.

And meant...
The technician is wrong - in that the ride will be worse, not better, with higher pressures.

Make more sense?

[Telmar]

I have been down this road, so to speak, and worn a set of tyres out in 8k cos Ford service advised 30psi .. and as others have said edges wear first. Since then on my previous FG XR6 I ran 38PSI (18IN) and on my current XR6 I am running 42 PSI (19IN) with approx 15K on tyres and no real evidence of wear.

[Evgeni]

I run 38psi all round. 215 60 16, standard suspension.
I do a fair whack of km's each week and I find at this pressure, the tyre wears evenly;i.e maximum contact patch.
I managed 108,000 out of a set of Bridgestone Turanza's with no rotation on the last set with 2mm to go before the wear indicator.
Got a set of Pirellis now, so will see how much I can stretch these.

[mik]

i think there`s a happy medium in tyre pressure, but it depends on what your after, maybe i`m old, but i don`t mind the softer ride, and i drive to look after my tyres, i also would also rather wear out tyres than suspension, as i reckon these days in particular with more performance oriented tyres, the tyres are a very minor part of shock/bump absorption compared to what they once where years ago, hence increased suspension/bush problems these days.
remember the old days when some cars with placarded tyre pressures of 24/26 pounds .

[EL.50]

I always run 38 psi, never had any problems

[Sox]

Bah, I need a proof reader!

My above post should also have read...
I personally never have less than 36psi in all 4 tyres.

[GK]

I run 38 in my tyres normally, then pump them up to 40-41 for a family trip.

Cheers,

GK

[peterljohnson55]

All your comments have been really helpful, as a group, and thanks to each one of you for your contribution.

Consequently, I'll ditch the recommended 30psi and go for 38 F and R, and 40-42 R for a loaded trip. Let's see how that goes.

Roads aren't too bad here in suburban Newcastle, except for those enigmatic speed humps.