DMcG
and vice versa on the remaining pair?

gnu
Yes - I am running around on gunk. I had three screws in tyres - one I replaced, the second was found during an MOT inspection (legal necessity every year here) which was safe and the now gunked one that caused deflation overnight. It is apparently a stupid adolescent practical joke round here, screws can be made to stay long enough to drive themselves in - I check before moving-off now every time.
The gunk inflates the tyre but you have to check pressure properly and drive fast enough to spread the stuff around with the <PEDANT=ON>centrepetal acceleration</PEDANT> of the wheel's revolutions.