I've been running mine at 275 PSI and have the 4" ventral fin - I've never scraped the tail.  Provides for a little softer ride during taxi.  To keep things pretty level on the ground I run my nose strut a little lower than normal as well.

 

If you watch my YouTube video titled "San Diego Lancair 2" you can see how it rides during the landing and taxi-in near the end of the video.  If you watch "Lancair Roll" you can observe more of the taxiing stuff as well.

 

Empty weight is 1050#.  Fuel capacity is 54-gallons.  Structurally the airframe was built to Lancair construction manual 320/360 specs regarding tail, fuselage & wings using standard landing gear with Ong's Debongers and the Ausie nose strut.