Roadies and techs are two different beings.
For the roadies, it can obviously vary, but a good rule of thumb would be 2 per department; a lead and an assistant. Depts usually include, Lights, sound, video, rigging, scenic, costumes and makeup, and Stage mgmt. sometimes some of these dept are combined or a single can be split into 2 or more depending on the needs of the show. Then you have the techs, there is usually 1 per band member and they are responsible for the instruments and any personal effects of the performer.
A large arena type show will hire local crew, alot of them. I’ve been on shows with over a hundred locals. And these are splint into 2 types: loadin and strike crew, and show crew. The show crew is not as big as the other, usually just a few locals, to do things like run spot lights and help with scenic shifts, or assist the other roadies if they need it.
And let’s not forget about FOH (front of house) such as merch, company managment (in charge of the logistics of moving all the personnel from one city to the next and lodging and food) There will usually be at least one rep from the producers, and reps from the agents of the performers. These reps dont usually travel with the show but they are always there, none the less.
Oh, and dont forget the truck drivers, there can easily be dozens of them. The largest show I’ve seen, was Pink Floyd, 32 semis FULL of gear!
So. . .not counting locals or truckers you could easily have 24-30 people traveling with a show like the Stones.