Valve stems in 17" Alloy wheels

[AlanD]

Hi all,

Had an interesting "fault" occur on the TDCi.

I replaced the valve caps with something "smarter" looking and one of them bound onto the rubber part of the valve stem, requiring signifigant torque to get it off.

A couple of days later I noticed the car pulling to the left, a check of tyre pressures showed the left front down to 24 PSI instead of the 34 PSI I normally run the tyres at.

After checking for a puncture and a leaking valve insert, I finally traced the problem to the valve stem becoming unseated, possibly because of the twisting to get the replacement cap off, and leaking air.

Inflating the tyre to 45 PSI and then adjusting to 34 PSI seems to have fixed the problem, but as the tyre case warns against pressures of greater than 40 PSI to seat the tyre beads I did so with some misgivings, but there were no adverse effects in doing this.

Something to watch out for if you have a slow "Puncture"

And it is clear that differential tyre pressures have a considerable effect on tracking, based on my experience I'm guessing 2 -3 PSI difference could be noticable on smooth level roads.

Cheers