Steve, when I had my (slightly modified) SAAB turbo in Thailand my philosophy re tyres was to use the correct speed rating (Z in my case) and would use them only till 40,000 km or two years, whichever came first. I did, on occasion, drive with a smile on my face but that was the exception rather than the rule. The tyres would start to feel a little less capable by then.
These days I drive a medium size SUV, so will stretch that to around 50,000 km or 3 years. By the 5 year mark, you can see the deterioration of the rubber compound, even on a new tyre. (I had a 'new' 7 year old spare. Even the tyre places won't touch it. So I typically change out the spare with one of the least worn ones when I change the set)
Ten years is really stretching it.