I run my Desser 8.50's at 15 lbs but usually let them get down to 10-12 before I add more air. Don't notice any difference in ease of landings in that pressure range, but the lower pressures are somewhat softer on a hard landing. I'm sure 10 lbs would be fine except that I don't want to continually have to check tire pressures. I am very afraid that much below 10 lbs greatly increases the chances for shearing off the tube valve stem on hard surface landings. For this reason I start higher and make sure they never get below 10 lbs.