The stock Puma tyres were 14 inch Pirelli CN36, 185/70 in front and 195/70 at the rear.
I previously found that the Puma is so light that it tends to aquaplane with wide tyres — instead of pushing the water out of the threads you just go over it. Unsafe, in a very interesting way. So I’d prefer to go with a narrower tyre. 185/65s are readily available because they fit on City Golfs.
Using the Wheel & Tyre Bible, the rolling diameter of a 185/70 is 1853mm and a 195/70 is 1895mm.
1. Rear: 185/65 have a rolling diameter of 1798mm. So for the same engine revs I’ll go 5% slower than the Puma specs.
2. Front: The stock Beetle wheel is (I think) 165/80 R15 with a diameter of 1945mm. This means my speedo (assuming an original Beetle speedo) will be out (high) by 8%.