Hi Dave,
We store our Eriba Triton on a gravel (25 mm average size) hard stand right at the bottom of our garden, but with the added fun of a right angle and slight up-slope before we can hitch up to our car.
The solid wheel was a problem - it just slipped through our quite large gravel. We replaced it with a pneumatic wheel and new jockey arm - which is so much better.
If you can use your car straight away, then it won't matter too much, but if you need to do any man handling or use a mover - then as Mark says, go for the pneumatic wheel.
Robert