welcome to the site 
looks like I`m the only one here, but I would toss any tire older than 6-7 years. From around that age you could be facing delamination. Perhaps you could drive another 10 years with them, but personally I would not take the risk. 
I agree with all above on the bfg`s... most are square to begin with 
No'you're not the only one Dutch.
I've been told tyres only have a reliable 5yr lifespan.
I'd toss them.
Just think of the damage a delaminaed tyre coud do to that beautiful car and it makes the decision easy.
