Tire pressure loss, no leak

[Slomove]

I have Bridgestone S03 installed (btw very satisfied) 195/50-15 on 6"rims. At the last track day (actually my first track day ) i was running them at 18psi. After one of the track sessions I noticed total pressure loss on the right front tire. However, no leak, pumped up again and is holding since.

 

I would suspect that I rolled the tires from the rim but I am not such a super hot driver and 18 psi doesn't sound too low either.

 

Anybody has an explanation for that?

 

The good news is that the Bridgestones are not grinding on the rim and drive reasonably well even with no pressure at all. Spare tire seems to be kind of redundant.

 

Gert

[Fred]

If you have a set of the caterham dust caps 🤔 Make sure the small o ring seal at the bottom of the cap is not pressing on the valve core when you tighten it up .Better still remove the o ring seal and chuck it . JUST A THOUGHT .

 

 

[Slomove]

No, just using regular dust caps and except adjusting pressure before the session, no other change. Pressure held for weeks before and after this happening.

 

Gert

[Chelspeed]

There was a problem with the old SLR 5 spoke alloys.

 

The tyre valve was positioned in the rim so that at high speed the valve itself would move (thrown outwards presumably) and break the seal at the base. The solution (short term) was to change to a stubby short valve about 1/2 inch long rather than the normal 2 inch long and (long term) move the valve position in the rim, so that it sat perpendicular to the rim rather than parallel presumably.

 

Could you have seen the same thing? Tyres would go flat but then once stationary pump back up perfectly, exactly what you decsribe.