Originally Posted by
ThePenIsMightier
Lag bolts sound excessive if you're tying into 4 studs, but it's not going to hurt. I bet 8 deck screws would have sufficed. Not engineering advise.
Anyway, the idea of larger pilots through the 2x10 is great, as long as the heads are big enough to still bite into the 2x10.
Any pilot hole is better than no pilot hole, so I wouldn't overthink it too much. Maybe try either 5/16" or 9/32" through the 2x10. But I'd err on the smaller side for the studs. Less than 3/16".