Radial tyres had been around since the 40's, with an 80 ( - 82%) aspect ration. Meaning that the side wall of a tyre was 80% of the width. So the side wall height of PIRELLI's the earlier 205VR15 CN72 CINTURATO ™ HS is 80% of 205mm which is 164mm meaning that this tyre would be 708mm. Because there was no choice when it came to the aspect ration of a tyre there was no need to mention that it had an 80% aspect ratio; However in todays descriptions it would be called a 205/80VR15.
Towards the end of the 60's when modern low profile tyres such as 205/70VR15, came about there was suddenly a need to specify this aspect ration so people knew they were buying the new technology, and wouldn't buy a tyre with a different diameter that would change the gearing or speedo reading of a car, so for instance the diameter of a 205/70VR15 will be (70% of 205 X 2 + 380mm =) 667mm.
In the 60's many cars like 250 GT Ferrari, E-type Jaguar, Morgan +8 or a DB5 would have fitted a 185VR15 PIRELLI CINTURATO ™ CA67 tyres. A 205/70VR15 tyre shares the same diameter as a 185VR15 tyre, so often, people want a wider tyre, using more modern technology. Under these Circumstances 205/70VR15 PIRELLI CN12 CINTURATO ™ HS will be an excellent option.
It is worth pointing out wider is not always a good option, as an example: when Jaguar started fitting 205/70VR15 tyres to their XJ6 in 1968, they did not fit it to the e type, because it did not handle so well on these wider tyres. It wasn't until they added power steering with the series 3 XKE that they fitted wider low profile 205/70VR15 tyres.
PIRELLI's 205/70VR15 CINTURATO ™ HS CN12 come s with the load & speed rating of 90 W meaning 600kg can be carried at a speed 170mph or 270kph for one hour continuously. These load and speed capabilities far exceed what any classic car owner is going to need on the road.
205/70VR15 tyres do tend to be fitted to extremely powerful sports cars of the 60's and 70's. The PIRELLI CINTURATO ™ CN12 205/70VR15 is the ideal tyre to fit a Citroen/Maserati SM, Jensen Interceptor, Morgan +8, Jaguar XKE V12, XJ6, XJ12 & XJS.