Do the tires first, and immediately after the alignment.
Most tire shops have a hook-up for a good alignment shop. But when you do an alignment, check to see what their machinery is. Newer ones are laser-guided, and should have a record of your stock specifications.
Just remember if you do have any modifications like lowered suspension, let the shop know. Sometimes, some setups won't allow a lowered car to drive right up. Other times, they need to compensate for the new specs.