Using boiling water won't get it too hot and cause damage.

Good idea - and also try counterintuitively twisting clockwise as well as anticlockwise, as the threads have probably 'welded' themselves together. This can happen when two different metals are left in tight contact with each other.......who was the pea-brain who thought metal dust caps were a good idea?

Edited by John F on 27/09/2021 at 17:29

As people may remember we bought a Nissan Pulsar a few years ago. Like the Leaf it uses valve based TPMS. Nissan clearly state in the handbook that METAL VALVECAPS MUST NOT BE USED WITH THESE VALVES.

Ours came with silver coloured plastic caps which are still fitted. No issues.

Don't blame Nissan though, not their fault. Blame the dealer or the stupid previous owner who fitted the metal caps. They should be sorting them FOC.

And when was the last time the OP checked the pressures. Or do they simply rely on the TPMS?

Edited by thunderbird on 29/09/2021 at 15:55

Never had TPMS and don't much want it, but expecting people who have it not to rely on it seems a bit unrealistic.

If you have never had it you will not be aware of its limitations. I will try and explain as simply as I can based on the 7 cars we have owned fitted with TPMS.

Whilst I understand some high end cars have displays that show the pressure at each corner we have yet to own a car that is capable of this. On all the cars we have owned all the system does is monitor either the pressure via the valve (1 car) or by the rotational speed of the tyre vis the ABS sensors (6 cars) and alert you via a "bong" and dash warning about a loss of pressure. Not even the car with valves (the Pulsar) indicated which corner it was, only way to do that was look around the car (all the tyres looked fine) and then check the pressures using a gauge which showed one corner was 3 psi low. Further investigation quickly discovered a screw so it was inflate the tyre to the correct pressure and dive to the local indy (less than a mile away) and get it sorted.

One major downfall of systems that measure the pressure using the ABS system to measure rotational speed is the simple fact that if all 4 tyres suffered a puncture at exactly the same time (not impossible, ran over a box of nails dropped by a van once that left me with at least one nail in every tyre - not just me affected and the company that owned the van paid for all the repairs) the system would potentially not alert you since all 4 corners could still be rotating at the same speed as each other.

So its not sensible to rely on TPMS, the handbooks for our 2 current cars both tell you to still check pressures monthly. Considering that many on here moan about to discontinuation of dipsticks on some cars its surprising that owners are quite happy to put their faith in a system with known shortcomings.

Would I go without TPMS, no way. Over the years its probably saved me buying 2 new tyres by allowing me to put on the spare as soon as the warning comes on. But I still do a monthly check.

Why on earth would anyone...Why not simply...

I said what I would do en passant, before suggesting another course of action for the OP.

I did not say the OP should use a flame, but I might do it because a flame is hotter and more likely to break corrosion. The finish on my wheels is not of concern.

I might not "simply" fit a plastic cap because I didn't have any and wouldn't want to faff around with internyet ordering and payment (always a slight risk) when there's a free solution to hand.

There may. however, be other reasons for not re-fitting the metal caps that I am not aware of.

Metal dust caps will fuse solid to the valve stem. The best way to remove them is to cut a slit in the side of the cap, insert a screwdriver and open up the slit. The caps are very soft metal and come off very easily. You will need new caps! £400 for this, somebody having a laugh!