The fair place to meet is El Paso, TX — the city closest to the midpoint of Phoenix and Tucson. From the farther side that’s about 7 hr 15 min of driving.
Recommended midpoint
El Paso, TX
From Phoenix
7 hr 15 min
345 mi to El Paso
From Tucson
5 hr 33 min
265 mi to El Paso
Tucson has the shorter trip; the split is off by about 1 hr 42 min. The alternatives below can even it out. Phoenix and Tucson are about 106 miles apart.
Phoenix and Tucson are about 106 miles apart by road. Split the difference and you arrive near El Paso, the city closest to the halfway point between them. That puts roughly 7 hr 15 min of driving on the Phoenix side and 5 hr 33 min on the Tucson side — the fairest single meeting point among the cities near the middle.
At this range, El Paso works for a same-day meetup: close enough from both Phoenix and Tucson to meet for lunch or an afternoon and still be home by evening.
If El Paso doesn't have what you're after, Las Vegas and Albuquerque are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Phoenix and Tucson.
El Paso is a city in and the county seat of El Paso County, Texas, United States. It is the 22nd-most populous city in the U.S., sixth-most populous city in Texas, and the most populous city in West Texas with a population of 678,815 at the 2020 census. Read more →
Phoenix is the capital and most populous city of the U.S. state of Arizona. With over 1.6 million residents at the 2020 census, Phoenix is the fifth-most populous city in the United States and the most populous state capital. Read more →
Tucson is the county seat of and the most populated city in Pima County, Arizona, United States. Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.