There's no airside connection between concourses A&B at TUS. That being said, TUS is a small airport and it might take ten or fifteen minutes to walk between the most distant gates, discounting time at TSA. TSA is hit or miss. Precheck (when it's available) isn't all that much quicker, because the bottleneck is at the id check, not the screening point. I travel thru TUS a lot and it's never taken me more than 15 minutes to get thru TSA so you should be fine.