A long trip exposes faults that city driving hides. Sustained highway speed puts continuous load on cooling, tires, and brakes in a way stop and go traffic never does, so the checks worth making before leaving are the ones a short commute never tests.
What does highway driving test that city driving does not?
Cooling is the clearest example. A radiator partially blocked with debris or a fan that hasquietly failed causes no trouble at 25 mph with air moving through the front of the car, andbecomes a roadside stop on a hot interstate with a loaded vehicle.
Tires are the second. A tire with internal damage from a pothole can run for months aroundthe city and fail under the heat and sustained load of highway speed. Check pressures cold,including the spare, and look at the sidewalls for bulges rather than only at tread depth.
Brake fluid matters here too. Moisture absorbed over years lowers the boiling point, whichis irrelevant in traffic and very relevant on a long descent with a loaded car.
Summer Road Trip Checklist: Questions
What goes on a summer road trip checklist?
A summer road trip checklist covers the cooling system, tire condition and pressure including the spare, brakes and brake fluid, the battery, and the wipers and lights.
Why check the cooling system before a long trip?
Sustained highway speed and summer heat load the cooling system continuously, which exposes weak hoses, fans and radiators that city driving hides.
Should I adjust tire pressure for a loaded car?
Yes. Many cars list a higher pressure for a full load; check the sticker on the door jamb.

