We had a tyre that kept deflating slowly. It would take about two weeks for the pressure to drop from 49psi to below 44psi. I would then inflate the tyre and normally it held the pressure for the journey. Eventually after about 2 years I removed the tyre and took it to a fitter who found not one, but two nails in the tyre. I had the tyre repaired.
The tyres were checked last year and found to be in a good condition all round even the one that had the punctures although they are now all over 5 years old.
I am uncertain whether to replace them this year or leave it until next year taking into consideration the tyre that had the slow puncture. Over the past 5 years and a bit years total mileage is less than 7000 miles.
Tyre size is 175/65 R14 90 and that is the problem as difficult to source a known brand name with a load rating of 90 that is not Chinese. However it does seem that I may not have any choice.