Tyre Pressures - What's the go?

[Mr White]

Hi guys,

Who has the good oil on tyre pressures?

What are the advantages and disadvantages of having your tyres at
low or high pressure?

What pressure is good to have my stock 18s at for daily driving?

How about for a spirited cruise, higher or lower?
Does a higher or lower tyre pressure give you more grip? When cornering?

Any noob type lessons, much appreciated!

[smythie]

Lower pressure on the road can be detrimental for fuel economy, tyre wear (the edges will wear before the centre) and water evacuation in the wet (the deformation of the tyre may cause the tread blocks to close up the grooves). I'd be guessing outright dry grip would be at the OEM pressure

Higher pressure can be detrimental for ride harshness, extreme high pressure for an extended period could cause the tyre to wear in the centre, outright dry grip may also be slightly compromised as you will have a smaller patch to grip the road with. On the flip side, you will have better response from the tyre when cornering and the tyre will be better able to evacuate standing water (tyre deforms less - tread blocks don't close the grooves so mcuh).

Well, that has been my experience anyway.

Personally, I run anywhere between 35 and 39psi regardless of the driving I do. I wouldn't knowingly head out into the hills with any less than 35.

[ultrablue]

i run 41 front and back but i have 19 inch rims

[Mr White]

Lower pressure on the road can be detrimental for fuel economy, tyre wear (the edges will wear before the centre) and water evacuation in the wet (the deformation of the tyre may cause the tread blocks to close up the grooves). I'd be guessing outright dry grip would be at the OEM pressure

Higher pressure can be detrimental for ride harshness, extreme high pressure for an extended period could cause the tyre to wear in the centre, outright dry grip may also be slightly compromised as you will have a smaller patch to grip the road with. On the flip side, you will have better response from the tyre when cornering and the tyre will be better able to evacuate standing water (tyre deforms less - tread blocks don't close the grooves so mcuh).

Well, that has been my experience anyway.

Personally, I run anywhere between 35 and 39psi regardless of the driving I do. I wouldn't knowingly head out into the hills with any less than 35.

Thanks for the comprehensive response Smythie.

So could i summarise that running at 36 PSI is better than what i currently
run (32 PSI) for pretty much all applications, with the only down side being
ride harshness?

When you were talking about the tyre wearing in the centre from extreme
high pressure, what's extreme? 40 PSI?

[smythie]

I don't know for sure, it might not be until 45 that the centre wears out.

If you have the RE050a's on the car I'd be happy with 32 or so (Bridgestone and Subaru would surely have an idea of the better pressure for an all round compromise). No need to go much higher around town, particularly if you have the dubious honour of driving around on Sydney's lovely road surfaces For a good run out of town I'd be looking at 35 or so.

[deucer]

38psi (cold) for 215/45/18's on a 3.0R-B. Running Bridgestone RE050A's. They get to about 41psi hot. Get even tread wear at this pressure. Keep your wheel alignment as neutral as possible and rotate/ balance every 10,000km.

[jdm rsk]

32 is way to low for the street you will wear out the edges of your tyres. i run 40psi on the road and that is not extreme

[THERB3]

Hey I have Potenza RE001 and I run 40 psi. Thats what I was instructed to run these and they are fine.

[Boxer]

Good starting point is the pressures recommended on the placard inside the drivers door (albeit these will be slightly biased to comfort more than performance). You usually get two recommendations - standard load and increased load (3 or more passengers)

I think the Subaru is around 33 front and 36 rear in this config.

Max pressure will be somewhere around 50PSI which is ridiculous for street radials anyway.

Everyone will have their personal preference and the higher you go the choppier the ride. Also it will vary tyre to tyre depending on tyre wall construction too and of course profile (so dont take anyones figures as gospel for you car and driving style)

My opinion is you wont wear outside edges until as low as 22-24PSI, but your tyres will be spongy and roll on the rims a bit before this.

I choose 37 front and 35 rear unloaded and if planning a long trip with a boot full then 37 all round.

40 is getting up there, particularly if you have well constructed tyres with good sidewalls and strength, but hey whatever works

[Sentinel]

Running 34's all round. Seems to be a good compromise for work trips and then a squirt around the mountains on the weekends without having to change the pressures all the time.

Prepping for Monday eh??!

[Mr White]

Prepping for Monday eh??!

yep . . . . . and for when i get my car back from tuning at HP-F

[Fangin_RX]

Well i Run 36 all round on my tyres found its a nice pressure

[nate]

I havent experimented too much yet with my lib, but in previous cars I have generally stuck to keeping it about 5psi under the OEM, having less pressure will affect your fuel economy, but it seems to stick to the road just that bit better.

[Sentinel]

Prepping for Monday eh??!

yep . . . . . and for when i get my car back from tuning at HP-F

Ah-huh... Will HP-F be done in time for Monday or???????

[Mr White]

Ah-huh... Will HP-F be done in time for Monday or???????

No