Tyres loosing air orf road?

Bin busy fixing ma hippo today. Noticed the tyres looked a bit low so I checked em. All part of me initiative to improve me mpg by +2 to get it back to 18mpg.

I have General Grabber AT2 tyres and they were set to 29.5 psi. Today I found they were all about 20 +- 1psi. So I changed the battery in me psi meter, and got the same result. So I checked em wiv me foot pump and got the same low reading. Didn't get round to checking the spare as it's late.

I can only think either all 4 tyres have gone down as the GG AT2’s don’t fit perfectly. Or could it be they went down due to going orf road? People keep telling me they looked low, but I didn’t think they were until lying by them and seeing how much tread was against the road. I’ve now set them to 32psi.

Alloys leaking
Mines got nitrogen in em, it stops the oxidisation and leaks

Could it be that whoever inflated them last had a faulty gauge, it has to be something that affects them all equally, if you check the spare & it is low also then it rules out offroad activity.

What you haven't told us is the time scale here - how long ago did you set them to 29.5psi?

I'm thinking perhaps the weather has a part in this.

The fall in temperature will affect the settings - but I wouldn't have thought as much as 8 or 9 psi even with a 20 degree drop - or would it?

Some clever dude who paid more attention at school than I did will be working it out according to Boyle's Law, or was it Archimedes, P=VT, or some such thing?

I wouldn't worry about this unduly - unless it happens again next week.

I don't think its any rim-leak or puncture, as the drop was equal and the chances of all 4 having damage is nil.

It will be interesting to know about the spare.

S.

Will check the spare later. Only thought about that as a comparison when all was packed up for the night and he'd bin on a test drive, then put to bed in the garage for the night.

Timings? don't think I've checked the tyres for a while. October last year perhaps. Will check em more often now to see if they're loosing air.

It was me who set the tyres to 29.5psi. Think I used the same meter as before. But would have also looked at the pump too so I'm hoping that rules it out. Well actually on second thought if I was the problem, then there wouldn't be a fault wiv ma hippo's wheels.

by the way, me vcu was 7.8 degrees before travelling to work 3.5 miles. 1.5 at 30mph in residentual type roads and the rest at 60mph. VCU was 16 degrees when I got to work.
Edit: air temp was about 8 degrees.

Looks like Santa brought you a digital thermometer gizmo!

Interesting - now we are going to get threads which are pages of statistics eh?

Seriously though - good idea to check the VCU more accurately - must check mine. Santa got me one last year but I haven't used it much.

S.

not got that many pennies to aquire such hi tech gismo's. put me hand on it and got it back ok but did hippo's VCU test and all fine at the mo. Did have problem with my tyres and turned out to be the tyre gauge on the compressor.

Had an infrared thermometer for some time but only found it recently. Maplin part no N92FX. They’re on offer regular for £20, which is half price. Checked the vcu temperature as a matter of caution. Think I’ll watch the temp more often to see what happens…

Measured the spare tyre this evening and it’s 21 psi. So all 5 tyres are roughly the same. Having thought about this I realised it may be the meter was giving the wrong information. Prior to changing the battery before, the meter was reading 15psi. After battery change it was 21psi. So it looks like a falt battery is the cause of the problem. After pumping up me tyres it now reads the same as me metal pen type psi gauge, which will be used as a backup in future.

I’ll watch the tyres to see if they go down again and if not, measure them in 2 weeks time to see if they’ve changed. I suspect they won’t go down. An important lesson to remember.

Having realised where the psi meter was made, its no surprise its fekin useless. I suspect foul play could still be the true cause. Even though we may have found the problem, I int ruling out the possibility one of the tratterers may have tampered wiv me meter. How else would the battery suddenly go flat...