Spent hours last night looking for these. The best one I could find which would fit the launch wheel 1” axel are these:
16 " PNEUMATIC WHEELBARROW WHEEL / INFLATABLE WHEEL - 4.80/4.00-8
https://rover.ebay.com/rover/0/0/0?m...2F222317885588
They are 15mm narrower than the sand hopper wheels are a regular tyre instead of the ‘squared off’ sand style, but I imagine 16” diameter versus 10” could make a difference. Maybe double up and go for 4 of these could be the best budget solution.
The lawnmower turf tyres look perfect. The problem is they would need converting to a 1” trailer hub to fit my launch wheels but they also look too wide to fit on the axle so that would probably need lengthening approx 2” which would require some custom machining. That plus the cost of the wheels themselves is getting incredibly expensive again :O
I like the look of those rollers though, they would definitely work although it’s a long beach!