banjodog replied:

Actually the valve cap is the “primary” seal for the valve stem not the valve. The valve is only there to stop the air coming out until you screw the cap back on – there is a rubber washer in the cap that seals against the top threaded area of the valve stem.

Whenever possible only use the metal valve caps as they seal better, are stronger and more robust than the plastic caps - and because the metal caps look good too they do get souvenired - I've had 3 sets taken over the years.

However, there are some good, strong plastic valve caps available too and are cheaper to buy.

Member - RockyOne replied:

I am a fusspot about always putting caps back on and never use those black plastic ones,Only steel ones with a proper seal rubber..Always keep at least two of my tyres with the valve caps that have the core remover slot on top..Good tip there about debri in tubes though..On trips up through the Gulf of Carpenteria,where,because of corrugations,all those in the know,had aired down to save the dashboard from falling in your lap,we noticed that every single punture we saw was through the sidewall..It gets worse..All were on the rear tyres..Lesson to be learned from that,as our tour leader indicated."Drive for your rear tyres,not the front" We came across a wagon of four folk,three tyres were staked through sidewall,all on the rear at the time..We lent them them a spare to get into Roper Bar,N.T..Oh yeah! .At servos,when airing up tyres,as soon as air chuck is removed,a little spit (what's a flash word for that? Expectoration? ;-) should be applied to valve opening to watch for bubbles which indicate leakage (soapy water if you just happen to have some in your kit)..Leaks a bit,press pin with little stick (who has matches these days and Bic™ liters won't fit) and let it slide off side to quickly release center valve pin..Mostly stops leak..Otherwise,replace..Yeah! I know..You old hands know all this,but we all had to start somewhere,way back in the burn on patches days..st.st.st!

We camped with a little snow.Woke next morn 200mm snow

spondo replied:

hey hey g'day

"Actually the valve cap is the “primary” seal for the valve stem not the valve."

this forum just keeps getting better and better.... lol

oh dear god give me strength
regards robs

Member - RockyOne replied:

"Front tyres flick up stones/nails etc" Yep! I found that out (different thread to the sidewall puntures/spikes tho) as I used to run a tandem trailer to the dump weekly wit 4 bald tyres..Never ever had a flat..Law tightened up after four years or so,then I but some "treaded" tyres on..You've guessed it..Had several puntures then,usually the rear...(did'nt need the tread for braking as the elect brakes had died years before)..(Not to be taken as evedence against me,as I speak with a forked tongue)