Tyre Pressures?

[Ray]

I've currently got 17" BA rims on my AU... usually i put about 35psi in my tyres, however a while back I had an incident where some little S**t let the air out of one of my tyres.

Anyways, took the tyre to my local Bob Jane to see what was wrong with it (I thought there was a hole at first) and when I got the tyre back, they'd put 40 (!!) Psi in it... just wondering whether that was OK to run them with that much air, or is it a risk?

oh, and tyres are 235/45R17's

[stiddy]

40-42psi would be MAX id say.. it will say the max psi to run on the tyre wall..

I was running 40psi in mine, im down to about 35psi now. The guys at bob jane said 40psi is too much.

[ClassicAU]

i have the same size tyres on mine, an i run 38psi all round. I would only go higher if you were carying a load or towing. But it also depends on how you like your ride, as the lower you go, the softer it will be, but that comes at a price of tyre ware.

Thats what i have been told anyway, can anyone else confirm this?

[Mechan1k]

I only go up to 40psi max when I am carrying heavy load (ie: 1 ton).
mid-30s is fine for 17"s (I am running 235/45R17 on a 17"x7.5" Territory wheel)

So far I have managed 40,000km out of my tyres and there's still a lot of tread left on all of them (although I have made sure alignment is checked regularly as well)

[AUCOON]

I run 40psi in mine 235/45/17 seems fine Bob Jane recommended that also getting excellent tyre life, on the side of my tyre it says that you can run 52psi max.

[Ray]

Thanks for the replies guys, looks like i'll be sticking to around 38-40psi from now on

[HLC]

i normally put 34-36 in mine... im running 225's on the standard fairmont rims which reccomment 215's... but cause i got nitrogen in them, i cant exactly top them up with air. i gotta take it back to bob jane and get them to fix em up and do an alignment.

[EvilChief]

Originally Posted by Ray

Thanks for the replies guys, looks like i'll be sticking to around 38-40psi from now on

spot on, most efficient level of pressure in regards to wear and economy

[shepv8]

I got Kumho Ecsta 234/45 17's and on the receipt/invoice from a reputable tyre place it clearly states " maintain a minimum of 40 psi at all times "
....interesting.

[The Monty]

Same wheels as yours, I run 36 up front and 32/4 up back depending.

[Casper]

Different tryes react differently to tyre pressures but I've found the 36-40psi range for 17" rims covers most of them. As I never tow or carry loads in the XR I stick to about 38psi front and rear and have never had major tyre wear issues.

[Autocade]

Originally Posted by Casper

Different tryes react differently to tyre pressures but I've found the 36-40psi range for 17" rims covers most of them. As I never tow or carry loads in the XR I stick to about 38psi front and rear and have never had major tyre wear issues.

Agreed minimum 36 on any 17' rubber
Ran a set of Dunlop 9000 at 30-32 psi and wiped them out in 26000 ks Ouch!
Have Goodyear Eagle F1 GSD3 now and they require at least 40 (dead cold) or they handle like a bucket of porridge and wear too quickly
I have run them up to 48 with no dramas except complaints from passengers that their fillings were falling out

[black ute]

40 psi is great for stuffing the centre of your tyre. Inside and outside may look good but thats mainly because only the middle of the tyre is being used.

[galaxy xr8]

I run 38psi in mine. no drama's here.

[Scott]

Agree Autocade.

Every body tells me about how bad it is to run high psi in street tyres because of the old addage of "you'll wear the centre out". IMO, this is true of 165/75, but not 235/45's or similar.

I ran my Pursuit Ute at 47 psi for 3 years straight and had perfect wear across the whole surface. I was driving on Continentals which were maxxed at 52psi and I drove that thing real hard. It would have been amongst the most flogged cars you'd see. I would rotate about every 10k's or so as the back would wear away and usually got about 40k's from a set.

Every one keeps telling me they'll wear out but I wonder how many people have actually run tyres through their whole life at a psi just below the max rating? Hard cornering will destroy a set of low profile tyres at sub 38psi, there's just too much flex and squishy for mine (usually resulting in understeer).

I've run psi like this for years on my low profile tyres, my cars get DRIVEN and they always get around 40k's from a set.

GT-P - 18's - 47psi
XR6 - 17's - 45psi
AU Pursuit - 17's - 47psi
EF Ghia - 16's - 43psi
EB Wgn - 15's - 34psi

If you have run high psi on low profiles for the life of your tyres and found differently, post it up!

[OZFORDAU]

Originally Posted by HLC

i normally put 34-36 in mine... im running 225's on the standard fairmont rims which reccomment 215's... but cause i got nitrogen in them, i cant exactly top them up with air. i gotta take it back to bob jane and get them to fix em up and do an alignment.

What exactly does Nitrogen do?

[JC]

Originally Posted by OZFORDAU

What exactly does Nitrogen do?

Not a thing for passenger cars. Air is 70% nitrogen anyway, so by putting 100% nitrogen in your tyres, you are only getting at best a 30% benefit. The latest copy of Street Machine scoffs at the use of nitrogen, except if you do a lot of track days, and even they said it was marginal.

I run my 18s at 40-42 PSI. 17s between 38 and 40.

[XR6-VCT-2000]

Have allways ran mine just a few psi below max unless towing or planning on a car full of people. My tyres have allways lasted their full life with even wear - with the exception of a set of Yokohama 352's 10 years ago or so which were rubbish imo , they gripped really well in dry - but the rubber compound was way to soft , they wore evenly but lasted only a few months ! ( and that was at around $250 a tyre for them back then too ! ). As mentioned above too though , depends how soft or hard you like your ride , and with a softer ride from less psi comes the expense of tyres wearing faster . Its all personal opinion really what psi you want to run them at, within reason of the max rating.

[Autocade]

Originally Posted by black ute

40 psi is great for stuffing the centre of your tyre. Inside and outside may look good but thats mainly because only the middle of the tyre is being used.

Black Ute

I have done 35000 on my current Goodyear Eagle F1 GSD at 40 psi plus and no centre wear
Wear is fairly even across the width and had them checked at Xmas at Beaurepaires said they would probably go another 10 to 15 ks
They also recomended running higher inflation as have many others with far more expertise than I have
Perhaps your particular brand requires less pressure or our driving styles may differ
As has been said and I agreed other brands may have different results but I have found higher pressures have worked out better for the brands I have used and that is why I have detailed them.
Furthermore I believe running at the low pressures recomended on the tyre placard cost me at least 1/3 the life of a set of Dunlop SP9000
I hope this does not happen to any one else
I would be very intersted to know what brand and size of tyres you are using and your experiences with them

[Autocade]

Originally Posted by OZFORDAU

What exactly does Nitrogen do?

I have been told it does not heat up as much therefore more stable tyre temps and less wear
I reckon if you were racing it would have benefits but I wonder if you would notice a difference on a street car

[CongoAU2]

Same in my 18in 235/40's I normally run around 42psi.