Which Snow Chains to buy? Konig T2 self tension OR Piranah or ????

You don't have to use diamond pattern, but they do provide better grip. I have a set of Pirahna chains, but have only used them in the mud on our farm. Helps a lot on the steep slopes. One thing with the Piranha was they didn't come with any instructions and I can't find any elsewhere. They're a bit fiddly to get on, but I haven't had any issues with them coming loose. Make sure the chains you buy will fit on your vehicle, including the front. If you put them on the front, ensure you have clearance when you turn the wheels if there's not much gap between your tyre and the guard. Some good advice on snow safety at Snowsafe.