Tyre Pressures

[2014GTi]

I have the 19" Santiago alloys wearing Pirelli P-Zero tyres.
Fuel cap says 41psi all round.
I wonder if the DCC spec cars need higher pressures in thier tyres?

[monkeyhanger]

I have the 19" Santiago alloys wearing Pirelli P-Zero tyres.
Fuel cap says 41psi all round.
I wonder if the DCC spec cars need higher pressures in thier tyres?

19" tyres need more pressure than 18", unsure whether the extra weight of the DCC system contributes also.

[corgi]

I wonder if the DCC spec cars need higher pressures in thier tyres?

What's the difference in weight between a DCC/non-DCC equipped car?

Do you think about putting extra air in the tyres each time you carry a passenger or do you vary tyre pressures depending on fuel load... if not I wouldn't worry and stick with the recommended...

[GiT1984]

The sticker in the petrol cap says 39/41psi from memory which is awfully high for a 1300/1400kg car. I'm guessing it's to help fuel economy.

Thanks!

This is spot on it's for the dreaded g/km figures - my Audi A3 Quattros sticker suggests Front 41 psi and Rear 39 psi also on 18's" (225/40/18) - makes the ride like concrete and wears out the centres. After much experimentation I've discovered at F38 and R35 are the ideals to wear the tyres evenly and give an acceptable ride / steering precision ...

[Buggaluggs]

The pressure for 225-45-17 written on the fuel cap says 29 for all.. Isn't it too low? I made 32 all..

Very strange! I can't reconcile how the larger tyres need higher pressures. If there is 29 pounds of pressure pushing outwards on the contact patch of a 17" tyre, then with the very slightly larger contact patch of a larger diameter tyre I would of thought a lower pressure would be needed, not higher!

...and so much variation between models etc also tells me VW are setting them up for economy not grip and even tyre tread contact.

The reason wider tyres require more pressure is to do with a couple of things, firstly wider often means lower profile ( say 225/35/19 as opposed to 225/40/18) and also the tyres core strength (steel belted, reinforced sidewalls etc) therefore more pressure is required to keep the wider section tyre flat and in contact with the road. I use a Michelin digital tyre compressor along with a Draper TPG100A tyre pressure gauge for that belt and braces approach!

[corgi]

There is another reason - apart from economy -  tyre pressures may be higher than you might expect, that is speed.

I suspect that the recommendations are the same for all markets including Germany. Where average motorway/autobahn speeds are higher (and could be significantly so) than here in the UK, for example. High speeds generate more heat through friction also lower tyre pressures generate more heat through greater sidewall flex. So, running at sustained high speeds requires higher tyre pressures to keep the tyres in their operating range.

So, there may be an argument for running tyre pressures slightly lower than recommended but this could have an impact on fuel economy and will impact handling, grip, traction and braking.

I personally run them to the recommended pressures, so don't take my statement above as recommendation on tyre pressures 

[jivemonkey]

My filler flap states under normal load, 36psi all around.

As I've just ticked over 1000 miles, thought I best check, so got myself a digital pressure gauge.

All four were at 41psi. F**king PDI my ar*e. My own fault for not checking regularly.

Anyone picking up soon, make sure this is added to the list of things to check!

[Ap69]

Be interesting to hear back from you whether or not it affects your mpg?

[jivemonkey]

Be interesting to hear back from you whether or not it affects your mpg?

Definitely. Will keep an eye out and let you know. Not sure how it will effect it though. Can it make that much of a difference? 

[Misterp]

My pressure sensor has just gone off. The petrol cap says 36psi all round. I only checked recently and set them all correctly. I will check again today.