18 inch tyre pressures

[Candyman]

It is not as simple as "this is the best pressure", even within a model

Your comment about those of us running 40 psi, I ran that for 3 years on my two sets of tyres with 45,000 km from each set. Golf GTI

Currently on 40 psi and 15,000 km. A Golf R.

The manufacturer placard will always err on the side of comfort ie low pressure compared to optimum for handling.

It isn't just load and temp, it is tyre compound, tyre sidewall depth, tyre tread, road surface and so on.

Running a low pressure to provide a better ride is not wise. Suspension provides ride quality.

Set tyres to provide the optimum for safety in handling and stopping.

[RosscoMK3]

Mr Holmes, I presume.
Lower pressures( within range) win out any day as far as stopping and handling are concerned.The lower pressures increase the contact area and increase the interface temperatures of a tire very quickly.
I remember my brother inlaw trying to tell me off years ago for running the tires in the lower range.
He is a breeder.

[Candyman]

Lower pressures, qualify please. Lower than what ?

Lower pressures can mean longer stopping distances, poorer cornering, sidewall rolling, tread malformation

[RosscoMK3]

Lower Pressures within the range specced by the manufacturer.
A lower end pressure can also mean the tire heats up faster when under strain. Heat equals increased pressure.
One thing I know for sure is that less pressure means more money on tires.

[Candyman]

How quick is the differential ?

Heat generated from surface contact, irrespective of pressure, can be regulated and managed in other ways and more effectively.

One thing I know for sure is excessive braking, sidewall rolling and poor alignment strips tyres much quicker

[RosscoMK3]

Jesus candyman. Im trying to watch the crow.

[random]

It is not as simple as "this is the best pressure", even within a model

Your comment about those of us running 40 psi, I ran that for 3 years on my two sets of tyres with 45,000 km from each set. Golf GTI

Currently on 40 psi and 15,000 km. A Golf R.

The manufacturer placard will always err on the side of comfort ie low pressure compared to optimum for handling.

It isn't just load and temp, it is tyre compound, tyre sidewall depth, tyre tread, road surface and so on.

Running a low pressure to provide a better ride is not wise. Suspension provides ride quality.

Set tyres to provide the optimum for safety in handling and stopping.

Yep, got that, so what Kms would you have got at some other pressure? After all it depends on tyre compound, tyre sidewall depth, tyre tread, road surface and so on, doesn't it?.

After my playing with pressure these last few days, I now know that ride quality is partly a function of tyre pressure. I bet my 34 psi GTD tyres have more grip on breaking than your 40 psi set, but just my opinion. Contact area.

The Manufacturer recommends changing the type pressure for the load in the car, not having a one pressure fits all mantra. Concerns about rolling sidewalls and deformation apply less to 18 inch tyres I suspect. Over-riding all of this is the driving style of the owner. The car is way more capable than I am am I just do not have the opportunity to push it anywhere near its limits, so I guess what works for some does not for me. This thread has really helped me, I had not even checked tyre pressure on my new machine before this, but I'm thinking now and its working for me.

[Candyman]

You will push it in an emergency, well beyond your skills

The time when you will regret not using tyre pressures optimal for handling as opposed to a slightly softer ride

Go with what you prefer. I'll go with what provides performance and safety and rely on my suspension to provide the ride

[MACCAA]

Mr Holmes, I presume.
Lower pressures( within range) win out any day as far as stopping and handling are concerned.The lower pressures increase the contact area and increase the interface temperatures of a tire very quickly.
I remember my brother inlaw trying to tell me off years ago for running the tires in the lower range.
He is a breeder.

Seriously?
You obviously haven't done much Driver Training or Tyre Testing.Or Motor Racing.....[Over 20 years worth]
I do both-and there's no way in Hell that lower pressures improve handling or reduce braking distances-quite the opposite.
We've done tests with wet and dry braking and lower pressures and the results are irrefutable.Not to mention the increased rolling resistance and higher fuel consumption.
The first thing we get people to do at a Track day is increase the pressures,otherwise tyres get destroyed in no time.
Candyman is spot on-the pressures on the placard are on the low side for comfort,not handling.
A couple of pounds extra can sharpen things up noticeably.
Lower pressures certainly increase the temperature-which is not what you want.Any increase in contact area is well and truly lost due to lack of sidewall stiffness,and rapid overheating.
There is not one tyre manufacturer that I know of who doesn't recommend more pressure for higher speed running.
We've got a Track Day at Marulan tomorrow.
The cars making the most tyre noise and attempting to leave the track in the process will be the ones that didn't increase their pressures as advised.
Your brother-in-law is right.

[RosscoMK3]

So you get them to run a higher cold pressure to achieve a lower running pressure while subject to extreme friction on the track? Am I on the right track here?
It sounds like you have plenty of experience and I'm always keen to learn something new. My only track experience is with the two wheeled variety.
I tend to drive my car on the road for the most part and usually for no more than 30 minutes at a time. How would this affect the running pressure and grip?
Would it be fair to say that the cold pressure of a tire is less important than the running pressure during the intended use?
I was under the impression that maximum contact, while maintaining the shape of the tyre, was best for handling and feel.