GATE - is this your 1st camper ? 1st Coach ?
because of our tank size weve only once come close to 3/4 full on our black tank and that took almost 4 weeks while visiting / parked on my MIL's curb.
even on a 3 day race weekend w/ 3 or 4 in the coach (dry camping) we generally dont fill the gray tank - and on the same type of weekend we're lucky if we use 1/4 of our fresh water.
for us - the gray tank always fills 1st...and i know others that have "leached" or trickled their gray (soapy) water on the ground after the sun goes down - most parks or campground frown upon this but its just soapy water.
Because Bob also mentioned - I would also recommend a TPMS system - it'll provide you at least some notice if not early warning of a tire failure...ive found its also saving me LOTS of time (no need to check tire pressure before a trip, just turn on the monitor)...no need to drag out air hose and attach it to a compressor (i use a co2 bottle now, but used to use the coach compressor).
I have the Truck Systems Technology TPMS system - lots of different axle configurations (capability to exceed 18 tires) & the TST system has the ability to add & drop a trailer or tow vehicle as needed. We dont always tow our jeep, but when we do, we monitor those tires too.
the TST system doesnt just monitor pressure, it also monitors tire TEMP (its one of the few if not the only system, that i know of that reports TEMPERATURE) - temp increases can signal failure or other issues (stuck brake, worn axle bearing, etc, as they will transfer heat to the tire too). The TST will set off its alarm if there are sudden PSI or TEMP rises or drops either in number or by percentage increase or decrease.
the
TST system will warn of over pressure or under pressure.
Like bob recommends - i would suggest a good FULL alignment & tire balance - i found a worn spring bushing on the rear of our coach that was causing some early tire wear & gentle pulling of the coach.