Peter wrote:
There are publications listing grass strips but most of the people whose strips appear in them are not too pleased about it.
The Italians seem to have a very nice system of grass strips, approved, known and published. It seems to very much “deliver the goods for the majority” as long as they don’t want to leave Italy…. the big compromise that makes it work legally. The UL guys fly around and have a good time. The land use doesn’t seem to be either ambiguous or illegal.
There have apparently been several A210s that had the noseleg collapse on grass, so I’m not surprised a school would stay away from unpaved runways
Mooney_Driver wrote:
Not even during your PPL Training? That is astonishing and makes me ask something about your flight school. Flying from grass is an integral part of a PPL and not having done that makes me wonder what else was left out.
I never did any grass flying either when I got my PPL, or snow, or frozen lakes. Grass is more forgiving than tarmac, or snow and ice. IMO their is no point in training on grass.
I use 31” Bushwheels for rough ground, but I keep a pair of “racing wheels” with planed 8.50 × 6 Goodyears for long trips to boring airfields. We plane most of the tread off because it only serves to trash the prop and the tail feathers.
For soft ground, inflation pressure, which equals ground pressure for a pneumatic tyre, is what matters most.
Conventional aircraft tyres can be run down to about 15 psi but lower than that could risk the tyre creeping around the rim. There are tricks to limit that, but perhaps not to be shared on a public forum.
Lower tyre inflation pressure means lower hydroplaning speed on water or wet runways, which might or might not be desirable.
Larger diameter tyres help to smooth travel over rocks, brush, rough ground and rabbit holes, but where Alaskan Bushwheels score on soft ground (and water) is that they can’t come off the rim, so they can be run all day at 8 psi (or less, in extremis). I cut one of mine open landing on a sharp rock this summer, and the aircraft remained perfectly controllable – albeit looking a bit lop-sided.
I’ve not noticed Bushwheels wearing on tarmac, but I do try to land as near to my parking space as possible. They get cut on rocks and sharp gravel, and the sidewalls crack a bit after a couple of years (UV perhaps). Still, they only cost 3 AMU a pair and you can’t put a price on carrying your runway with you…
I’ve never heard of balancing aircraft tyres, but I suppose it wouldn’t hurt for nice aeroplanes. For Maules, Cubs and similar aerotrash we are only running at more than 30 mph for a second or two, during which time the driver is too preoccupied with the various knobs, sticks, pedals and levers to notice any vibration or bumps.
Conventional undercarriage obviously allows more effective braking until the aircraft is almost stopped, whereupon trikes have the advantage of a training wheel under the prop. 
