The clerks are good at the keyboard and application guides (probably designed with a lawyer over their shoulder) You need to know your stuff and insist on what YOU want. That's what I do.

The tire doesn't know if you drive an Xterra or a Crown Victoria. A P rated is also sufficient. There are lots of studless tires available in 245/75-16. Some tires are squirelly (due to the thread, not due to the vehicle weight). This measurement is not designed for sports car or sedans, so... It doesn't take a scientist to determine they're for vehicles in our categorie.

These are listed for SUV:
Michelin Latitude X-Ice
Bridgestone Blizzak W965 is LT rated
Continental ExtremeWinterContact
BFGoodrich Winter Slalom KSI
General Altimax Arctic Winter is LT rated
Bridgestone Blizzak DM-V1 "...new standard for light truck and SUV winter tire performance"
Toyo Open Country G-02 plus LT rated
Toyo Open Country WLT1
Yokohama Geolandar I/T G072

You're not jeopardizing your life with a 245, whatever the clerk says. Tacoma are running 245/75-16. If owner ask a clerk to install 265, he will tell him he cannot!!! Yet Tacoma and Xterra are similar in size. Pick what YOU need.

During winter driving you're jeopardizing more with 265 though...

Good luck!