Tyre Pressures

[Guest Brent400]

RICHDAVE, How many Km's do you have on your tyres?

Brent

[HellionXR6T]

Hmmm, seem to be a few variants here.

I do a lot of highway driving, therefore I don't think I need tyres pumped up past 42psi, some of the roads near Ipswich are not exactly the best quality.

Do you think36/38psi might be the go? Currently only running 35psi. I might give it a go.

[Turbo6man]

Hmmm, seem to be a few variants here.

I do a lot of highway driving, therefore I don't think I need tyres pumped up past 42psi

This is a bit of a contradiction isn't it?

I mean on the highway is presumably where you are going to be operating the vehicle at higher speeds - and possibly putting extra cornering demands on your tyres. Both these things lead to higher temperatures in the tyres and therefore higher wear rate. The higher (cold) pressure helps to overcome these problems.

And then also there's the safety consideration - your vehicle will respond to steering input more quickly with higher pressures - I would expect this is something you would consider important if you do a lot of highway miles.

Fuel economy may also improve marginally if you lift your pressures by a few psi all round (from the 35 you say you are now running).

Generally you need higher pressure in the front over the rears - I suggest by about 4 psi. You can bump the rears up by 4 psi if towing or carrying four or five adults for a long distance.

Finally, to repeat my suggestions for best wear/comfort compromise :- 40 front and 36 rear for general all round driving. Go higher for consistent high speed or track work. You can use these pressures with 17s or 18s but you might like to play around with plus or minus 2 psi to suit your own driving style and needs.

[HellionXR6T]

This is a bit of a contradiction isn't it?

I mean on the highway is presumably where you are going to be operating the vehicle at higher speeds - and possibly putting extra cornering demands on your tyres. Both these things lead to higher temperatures in the tyres and therefore higher wear rate. The higher (cold) pressure helps to overcome these problems.

This is why I thought I'd raise the question, I'm no expert on the subject and I'm sick to death getting a different answer so I'll ask you guys.

THE ONE's DRIVING THE DAMN VECHICLES!

I was sick to death with one company saying "Yes, pump them up to around 42 all round". Another mob stating that there was way too much pressure in the tyres. and reduce it on me to 32-35psi.

I'll take your advice. 40psi front 36psi rear, see how it goes.

Thanx..... :spacecraft:

[saleen]

FYI I was recommended by Bob Jane to run my 19's at 34psi.

Rob

[HellionXR6T]

Running 36psi rear, 39psi front and it's sooo responsive. I thought I'd feel every single imperfection on the road but the ride was surprizingly smoooooth. Think I'll keep it where it is. Very happy.

Thanks.

[Turbo6man]

FYI I was recommended by Bob Jane to run my 19's at 34psi.

Rob

Bob Jane sure like selling tyres eh? ... and lots of them if people follow this type of advice.

So if they say 34psi for a 19 I wonder what they would have you run standard 15s or 16s at?

Basically, the lower the profile of the tyre the more pressure you need to run to prevent heat, wear and sidewall damage.

34 psi is OK for a 65 or 70 series radial.

[saleen]

Bob Jane sure like selling tyres eh? ... and lots of them if people follow this type of advice.

So if they say 34psi for a 19 I wonder what they would have you run standard 15s or 16s at?

Basically, the lower the profile of the tyre the more pressure you need to run to prevent heat, wear and sidewall damage.

34 psi is OK for a 65 or 70 series radial.

Thanks for the info Turboman

Well, the funny thing is, I though the dude said 32 psi, so that's what I've been maintaining them at until last week when I realised the card said 34 psi. I've now nearly done 10,000k's on them and no sign of wear at all. But just for the hell of it, I'm gonna try pumping them up a bit, to maybe say 36 or 37 see what its like. If its too harsh, they are going straight down to 34 as recommended, I don't pay for tyres anyway!

Rob

[NT TURBO]

Sorry if this is a stupid question but how long does it take for the standard dunlops to warm up, how much does the pressure increase when hot?

Basically what I'm want to know is driving normally about a k to the nearest servo putting much heat into them and is it really worth waiting till there cool again, remebering its still "summer" here? And lets face it the tyres arent always cold whens its noticed one has lost pressure for one reason or another is their a rule of thumb to compensate for hot tyres?

[aaronmihe]

Ahhhh found this thread so don't have to start my own

When I took delivery of the car I didn't check the tyres (all of 7 days ago today) and was driving it aroudn for a couple of days forming my own opinions and getting the 'feel of the car'.

Anyway I kept thinking it wasn't turning in properly.. and under power was having a fine wobble that either suggested poor suspension control or similar.

Anyway the other night a check confirmed, different pressures across the front axle (27L, 31R IIRC) and a low 27psi across the rear axle.

Not bothering to even look at the placard and knowing from previous car experience that about 36-40psi would be a good starting point we set 38psi all round.

Much improved handling, no squirm from the rear end and even turn-in... Very happy.

I'm tempted to go a little higher after reading this thread but we'll see how the 38 holds up for a while first.

As for the cold/warm filling... I tend to dive to the nearest servo when the tyres are cold (say 1km) and inflate to chosen pressure measured with good guage (or the digital guages now available at many servos) and then try it.

Tyre pressure choice is a personal choice thing up to a point. You can vary handling balance and responsiveness through small changes and in one make racing it's been long proven that tyre pressures can be a deciding performance factor.

A.