fault or low tyre pressure???

[golfgti10]

the dash board light is on, ive just changed the wheels from 225/45/17 to 225/40/18 would this just be a tyre pressure problem?

if so what psi should I have in the new tyres?

[Marc-5-GTI]

It's cause you've changed wheels mate... The PSI will be on the side of the tyre and in the filler cap IIRC

Just hold the tyre set button in for a while till the light goes off 

[Scottymon]

38/40 I put in the 18's... once pumped, hold down the button until the light goes out.

[golfgti10]

do I just press the button or do I have the key in or what???

[Scottymon]

I've always done it with the car running, but probably does it with just the iginition on.

[Marc-5-GTI]

As above