I didn't get the Klebers in the end, I went with a set of Vredestein Quatrac 5. Absolutely superb in the wet and as good as dedicated winter tyres in snow, very quiet too. Seem to be lasting rather well, they've done at least 35,000 miles and still have plenty of tread, well over the 4mm minimum needed in some European countries in winter. No idea if they are available in the size needed for all wheels though.

+1 on BF Goodrich AT - they're standard on the 50th Defender as 265/75 R16, and seem to last 40k+ miles. On the P38 i'm using 255/55 R18 Goodyear efficiency at the mo, c 140 pounds fitted and balanced

I've now got AT3 on my Jeep and so far I'm very impressed. I've done several motorway hours, general commuting and some very basic running around on tracks and grass at work - no issues with traction. They're smooth and quiet on tarmac and cost me £100 a corner (235/75r15). They're MnS, Snowflake rated, 75dB noise rating and score a B on Wet Braking.
If they last as long as the AT2s did (53k miles) I'll be chuffed to bits.

Available sizes: https://www.cranleigh-tyres.co.uk/Tyre/Details/General/Grabber+AT+3