I created these wheels to get more grip on a clay-like ground that is moist. We have very wet grounds here and the normale wheels would just fill up with mud and be very smooth and then dig holes in my grass.

This fixes that problem! I would combine it with a weight to make it even better!

This upgrade was made for the M500 / WR141E but I'm guessing it also works with the WR165E and WR167E and WR142E and WR143E. Not tested, but hey look VERY similar to this one!