Tyre pressures- on road

Barnboy

Forum Member
Joined
Feb 16, 2010
Messages
121
Location
Suffolk, UK
Car Year
2012
Car Model
Forester
Transmission
Manual
I have had a look around and can't find any info about tyre pressures for standard road driving (yeah I know it is an Offroad forum).

I have an SF Forester and am running 215 75 15 Goodyear Wrangler ATs and have been running them at about 35psi, which improves the handling over standard subaru recommended tyre pressures, but noticed the middle of the tyres is wearing more than edges.

What pressure is anyone else running for just normal driving?

I have never really known if you go for a bigger than standard tyre if you need to up the pressures or not...

Think I will drop the pressures a bit and try to even the wear up a bit.

Cheers

Tim
 
Unladen, I run 32-34 front and 30-32 rear
 
Perhaps i will just try dropping a little to what you are running Kevin. I know when I first changed tyres I found anything under 30 felt a bit like steering a boat .
 
Kevin said:
I run 32-34 front and 30-32 rear
Click to expand...

+1 I run similar in my 215/70R15 Geolander AT-S, any less and its like a boat. Any more helps abit with cornering but was wearing in the middle. I ran 36psi all round for 7months and only reciently changed to similar as Kevin.
 
^ yeah, I used to run about 36 as well but, with my suspension, found it too harsh unladen. With a load on, 36-38 is fine.
 
I used to run mine at 38psi on the front & 36psi for the rear.
I have since changed to 36psi all round.
And I have Geolander AT-S 215/65/16's by the way.

Regards
Mr Turbo
 
I read somewhere not long ago something about the 4psi rule. It goes a bit like this:

- Measure your pressures cold (as in with the car resting overnight).
- Take it for an hour's drive in the terrain of interest - say bitumen
- Measure pressure hot. If difference is 4psi, then you've got the right starting pressure. If more, then you started too low and conversely if less, then you had initial pressure too high.

If nothing else, at least it keeps you entertained over a long journey...

Pedro.
 
Might give that a shot some time. Thanks Pedro :biggrin:

I just checked my tyre pressure warm. one was at 16psi, one at 22, one 32 and the other 33. lol. Might have to check for a few puntures, no biggy :iconwink:
 
Tyre is definitely over inflated if the centre of the tread is wearing. Drop it down a few psi and you'll find you have more grip. Just don't go too far the other way!
 
Thanks for all the great responses. I think part of the reason for going higher was simply to make the car handle better with the bigger tyres, but will defo drop the pressures now.

Really like the idea of the 4psi rule, something to have a play around with..

Having posted this to start with, did wonder if I should have done the tyre pressures in bar, glad to see psi works with everyone.

I think I will take a look at changing my springs soon, as running fairly new standard shocks, but guess an uprated spring will help the handling a lot. The standard springs are pretty poor to start with in my view, well at least for carrying any load in the car.

Thanks again

Tim
 
I think the only time you want to speak bar is when you are thirsty.
 
I put 40psi in my tyres for the drive to Mt Isa. It was suggested because of the high temps experienced does weird things to tyres.
 
I have 38 in my car in the front. It will be a combination of hot tarmac, high speeds and high lateral loads that will put heat into the tyre. If you are running too much pressure and the centre of the tyre takes all the load.

Species said:
I put 40psi in my tyres for the drive to Mt Isa. It was suggested because of the high temps experienced does weird things to tyres.
Click to expand...
 
Gidday All

When I got Roo2, I set the pressures up at manufacturer's specs +2 psi. This has worked well for every car I have owned till then.

Roo2 handled OK at this (31F/30R), but certainly nothing spectacular!
It currently has Pirelli P7s fitted.

A week or two ago I upped this to 36F/35R.

The difference is amazing. The handling is much more like Roo1 (93 Impreza). The ride is no harsher than it was before. If anything it actually rides better over 'sharp' speed humps etc. Go figure ... :exclaim:

Steering is more precise, even at slow speeds around roundabouts. The slight 'floating' feeling has gone. Directional stability has improved (zero tendency to wander in the lane now).

The other thing is that the tyres were showing some shoulder wear. Classic sign of under-inflation if they are not scrubbing on one side or the other.

Best to work this out before I fork out for a set of Geolandar AT-s, I reckon.
 
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