18 inch tyre pressures

[random]

The fuel flap lists three pressure ranges for the three main tyre sizes and after deciphering the symbols it does list half load as 240. The sticker is a table and I was reading it as different pressures for the different type sizes, but it is for different loads. Wow, gunna try that on the way to work.

I've done 4500 now with the full load pressures. In fact the rear were a pound or two higher, no wonder it was slightly rougher than necessary. Thanks for the prompt.

[brad]

If you want a good pressure gauge, this is the place to look

[random]

Did 60 Kms today with the recommended pressure for unloaded. Really very happy dubber now. Still have the nice controlled feeling with comfort. 43 in the unloaded back-end was not good.

The higher the pressure the less contact area, so there must be a pressure point where the grip reduces and contact is compromised by tire skip. Contact area in Contact area (sq inches)=Axel load (pounds)/tire pressure (psi).

[csf6701]

For my GTi on 18" rims it was 260kpa ( est at 37 lb ) for all tyres for highway driving. Didn't have an issue for a few months then one day driving from Sydney to Canberra the low tyre pressure warning light came on. Inspected the tyres all looked ok but just to be on the safe side drove the last 75km @ 80km/hr. *groan*

Checked the tyres when cold no loss of pressure but warning light stayed on. I booked the car into the local VW dealer and was advised issue caused by having the pressure too high. The recommended pressure was to run 34 lb/ sq in all round.

Since then have no further issues with the warning light and the ride feels better.

[Candyman]

Which VW dealer ?

Just so I don't use them.

[brad]

For my GTi on 18" rims it was 260kpa ( est at 37 lb ) for all tyres for highway driving. Didn't have an issue for a few months then one day driving from Sydney to Canberra the low tyre pressure warning light came on. Inspected the tyres all looked ok but just to be on the safe side drove the last 75km @ 80km/hr. *groan*

Checked the tyres when cold no loss of pressure but warning light stayed on. I booked the car into the local VW dealer and was advised issue caused by having the pressure too high. The recommended pressure was to run 34 lb/ sq in all round.

Since then have no further issues with the warning light and the ride feels better.

Dealer has fed you a load of bollocks. Hope they were tasty.

[kash_0]

Mine are on 38 all round...no issues to report

[RosscoMK3]

Interesting thread.
I'm running mine(17inch I think) highend and they are showing signs of wear on the middle of the tire. No ****e Sherlock.
At high running pressure the road feels closer and the tires slide out easier under hard cornering and acceleration.
When I had my motorbike I ran really low pressures and had great response and grip once they were warm. They shredded pretty quickly though.
IME, run tires as low as possible without going below the manfacturers advice. Way better handling and comfort.

[random]

Interesting thread.
I'm running mine(17inch I think) highend and they are showing signs of wear on the middle of the tire. No ****e Sherlock.
At high running pressure the road feels closer and the tires slide out easier under hard cornering and acceleration.
When I had my motorbike I ran really low pressures and had great response and grip once they were warm. They shredded pretty quickly though.
IME, run tires as low as possible without going below the manfacturers advice. Way better handling and comfort.

Its about contact area. The contact area reduces as the pressure goes up. Think about it, the 20 psi has double the contact area as 40 psi as it has to support exactly the same mass of car. So at some point this side of rock hard, the contact area reduces and the tyre compound is exposed to high wearing loads, usually in the centre. Too low an bad things happen too, wear on the outer edges being one. So for every load and temperature there is an optimum pressure. Given that most of us only have one person in the car, the driver, that sweet spot must be somewhere on the low end of the recommended range.

On the sticker it has 240 for two people and one or two bags. Sooo, with just me going to work I rounded it down to 230 and it seems great. So I probably have the same type contact area as someone running 40 psi with four in the car and some shopping in the back. So for the warriors running 40 on light loads I'm not sure that either the types or the ride will thank you. But I know that my GTD and I are smiling now.

[RosscoMK3]

Elementary my dear Watson.