I am just about to leave for a long road trip from Wales to Spain and decided to check the tires. The tire guy said I should change them all as they were 10 yrs old.
I went home doubting him as the treads were like new. However, The following day I decided not to risk it and have them changed.
Well thank the lord I did, when he took them off they were totally out of shape, more like an egg than a wheel. It was a disaster averted. I can now go with confidence.