For now I’ve taken the Duratracs off and gone back to stock. I think perhaps I just got unlucky, others report good things about the Duratrac. The other issue was the sheer amount of additional drag on the road, leading to massively worse mpg. It was really noticeable.

There are plenty of options in 275/55/20 or 265/55/20 and I think I’ll explore those at a later date.