Having a good chat to my Dad and a friend on Saturday morning, and we were discussing old tyres, specifically the 155 Firestone F-560s on the front of my project car. Lee thinks that the tyres are too old to use, whereas I've given them a good check over and there are no signs of perishing or cracking. Dad said that he thought the rubber seemed too shiny on the tread, almost like plastic, and was concerned that the tyres are too hard and just wouldn't grip, especially with the front disc brakes. I've used Firestone F-560s before and they've always been a hard tyre. I don't think I've ever worn one out!

I don't know how old the tyres are - they came on the wheels I'm using that I bought three or four years ago, and I don't know how long they'd been on a car before that.
So, three questions:
How old does a vintage tyre have to be to be unsafe?
Is there any way of breathing life into an old tyre? Grip juice? Rubber softener?
What is the correct way of storing tyres to prolong their life? (I'm asking this one because I'm getting another pair of 145 XZXs off BenSSP and I've got a fair collection of wheels and tyres I want to last!)
Thanks!
