Tyre pressure change and ACC

[ncomben]

Good morning my fellow rockers.

After cleaning my car yesterday I thought it was about time I checked the tyre pressures (I've only had my car a couple of months now). I was quite shocked to see that all four tyres were 28psi when the recommended level was 33psi - but after reading on this site about dealers and tyre pressure I'm glad that at least they were all the same!

Anyway, on to the question. For my every day driving, as I live in Surrey and our roads are the worst in the country (despite having the greatest density of road traffic), I set the ACC to comfort. This morning, on my commute, the ride seemed much firmer, equivalent to the normal setting on the old tyre pressure. How long should it take for the suspension to accommodate the new pressure or is the firmness indicative of the higher pressure?

Thanks

Nathan

[RW1]

ACC adjustment has no learning period like that. It does adjust to how the Scirocco is being driven in each setting, with the adjustments being fairly quickly executed. The change you are experiencing is the tyre pressure adjustment. 5 psi is fairly significant to make such a change to the ride that you would notice.

33psi maybe recommended but it can lead to centre area band of the tyre wearing quicker than the outer and inner area bands. More pronounced on the front tyres. You will need to keep an eye on the wear rate.

I set my tyres to 30psi once I noticed and generally the wear rate has then been even across the tyres since. This appears to have been the best compromise for my tyres (Bridgestone Potenza). At this lower pressure, the road holding is better, (but they still do a merry dance on some wet bad condition tarmac corners but thats the tyre - poor.)

And don't forget, tyre gauges are generally inaccurate. I have 2 pencil types, a pump gauge and electronic one. The pencil & pump ones read differently with an overall spread of 3 psi in reading variance.

C.

[ncomben]

Thanks for your reply RW1. I suspect the dealer reduced the pressure to make the ride softer and a bit more palatable for me since I was driving an A4 SE at the time.

Straight away, I noticed that the fuel economy seems to be better so I'll leave the tyres for the rest of the week and see how I get on, but I suspect that by the weekend I will drop them a few PSI.