[woodcote]

The chart is useful, but only when you gradually get used to it - and I am not far beyond beginner level...

   

The stock tyres are C1s, so look across the top part, which divides all the tyres by compounds. In the C1 column is the 1228C2 - that’s a typo and it should be 1228C1.

Moving to the bottom part of the chart, take the stock rear wheel size (usually on the Pendles website) - 15.8 x 8.2 - from the left column and the stock tyre - 1228C1 - from the column headers and you get a 19.8 diameter for that combo of tyre on wheel.

We’re now looking for an F22 compound that fits that hub and gives a diameter on the stock wheel of approx 19.8. The top part of the chart gives three F22 tyres. Finding them in the column headers of the bottom part of the chart shows only two will fit the 15.8 wheels. The PT27s will measure 19.7 and the 1207s will be 19.6. I suspect both will be absolutely fine. The final figure in each column also shows the width - at 10mm, they are very slightly wider than the stock tyres, but that should also be absolutely fine.

The dwg figure is, I believe, the specific mould for the tyre. Some part numbers contain the dwg and the compound (eg 1207F22), but most do not. If you are looking for tyres with different compounds but from exactly the same mould, look at those grouped together in a single column header and then cross-reference with the compounds in the top part of the chart.

All quite labyrinthine, but vaguely satisfying when you think you’ve cracked it... I’m now fully expecting someone to come along and point out my errors!