The wheels are branded CLM on a snipe trailer and are the type with two pressings welded together. They are rated to 500kgs each and the whole boat and trailer weighs less than 750kg cos its unbraked (really! I worked it out including all the additions!)
Kit isn't carried in the boat except when launching at the bottom of the hill about a mile from the house, when travelling any further than that it goes in the car and the other wheel looks OK, even with kit it would still be well under the wheel rating as never more than two sets of twins are ever carried or launched in the boat ever, any more gets loaded after launching.
The cracks aren't between the nut holes but about an inch outside with the crack travelling all the way round nearly. If it broke I would have had the whole disc still attached about an inch bigger than the nuts holding the wheel on.
Having problems with Snipe at the moment, they agreed to sell me a pair of wheels for the price of one after seeing the picture then overcharged me enough that for £9 more I could have bought two identical wheels from my local supplier, still waiting for a call back after complaining