Why are most air ride gauges 200psi?

[t300]

Seems as though a lot of posts here indicate guys are running anywhere from 60-90psi up front, and a lot less in the back. Most gauges I see advertised for sale (including board vendor kits) are 200psi units. It would seem to me that a 100psi gauge would give a lot more resolution on what PSI you are actually running. At a glance, I can barely tell what the rear of my truck is at within 10psi. Its a manual setup and I like to target certain PSI so my ride height (and therefore alignment) is consistent.

Am I missing something?

May as well throw out a pic of my '70, running on SS7's and manual valve setup from Travis @ AZPro. Love the truck!

Matt