I wish Professor Kevin would come and comment on this!

 

To get enough ground clearance to drive over a matchbox....

 

I agree his pressures are too low.

Forget the tyre placard - that's lowest common denominator stuff (literally). Just about any driving instructor will tell you even the average sedan should be running higher pressures to improve handling and braking.

I run 36psi usually but if I'm going to be on the freeway for extended periods, I up that to 38-40psi. Another good tip I learnt long ago was never trust the gauges on servo air hoses - always carry your own.

 

Measuring your tyre cold is all a guestimate!

You drive in different condition and different attitude.

One day you are in a A-B mood, one day is not.

How are you to judge which tyre pressure to have on your rubber.

Just relax I will say .

Drop some pressure before you go for a "fang" is advisable. For A-B, pump as Revolver or a bit higher if you got traffic.

 

always a good idea to increase your psi (tyre pressure that is) when you on a long distance trip (freeway/highway) with "heavier" load.

 

Well of course it is but not all of us jump at out every set of lights to check them again. You have to have some means of checking the damn things.

I quite agree there's a fair range for street use depending on the tyre from, say, 33-42psi that's appropriate, but I don't think going lower than that is advisable unless you're going to be punting it VERY hard or going on the track.

 

Agreed Kall, that's why I said this:

I have a bit of a thing about people who under-inflate their tyres or still stick to the hackneyed idea of 30psi cold no matter what, simply because that's what the tyre manufacturer sticks on the placard.

I'll often bore 'er indoors silly by spotting under-inflated tyres in traffic and have been known to advise some drivers to get their tyre pressure checked.

Actually, it's often larger 4WD's that have an under-inflated rear tyre from my observations, to the extent that the tilt of the body is noticeable from a casual glance. Yes, the same behemoths with an already poor braking distance that drive through school zones at peak kid times. Great, isn't it?

I'm not suggesting that User24 falls into that category btw, just that his tyre pressure might have played a part in the car's reaction (particularly given his description of sawing back and forth on the steering wheel).

 

Time to get scientific (stop the groaning out there). I mean, let's measure something! You'll know if your tyre pressures are right if the tread depth is uniform across the profile. Get those calipers out! If the pressure is too low, tread depth will be more in the middle of the tyre. Too high, and the depth in the middle will be shallower. I think that Revolver's 36psi is about right for 235's. I'm running 245's and I'm using 260kPa (=38psi). I also agree you should use your own (trusted) gauge. To that I'd add: measure when the tyre is cool (before driving out of the garage in the morning, say). Trying to hold measuring conditions constant is important. As the tyre heats up, the pressure will increase.

 

I find if I pump them up much beyond 34(psi) the car tends to jump around alot more and the steering becomes quite light which im not to fond of.. just my preference,

I have the standard 225/45/18.. so by labrats figures i think im about right?

Also i seem to have missed this "2 option" dsc thing, so if you hold it down for ten or so seconds rather than just pressing it, you completely disable the driver aids except abs ??

New Zealand has some of the wettest roads i beleave, I hardly ever dont turn the dsc off but the times i have experienced with it, It does what its surpossed to do quite nicely..

 

Ride does suffer a little beyond 36psi for me, but then again I'm running MS suspension and Whiteline sways, so it's stiffer anyway. This generally becomes a personal preference thing in the range I mentioned. I certainly agree 34psi for the stock rubber is fine if that's the ride/handling compromise that suits you.

You're correct about your DSC comment.

I'd leave it on in NZ too!

 

Oh yeah! Had a number of little DSC "shimmies" in the wet where it's telling me to constrain my exuberance.