And he knows that's exactly where the Hammers can hurt Arsenal at Upton Park later today.
"Arsenal have conceded goals more than should be doing for a team of that calibre and that’s where we can hurt them because we’ve got goals in abundance," the West Ham defender is quoted as saying by the Daily Mail, in an interview that will also be included in West Ham's matchday programme.
Tomkins, however, is also wary of the Gunners' threat going forward - and he would be remiss not to mention Alexis Sanchez.
"I’ve seen Arsenal play quite a lot this season and I like to watch Spanish football so, I’ve seen Sanchez play for Barcelona and know what he’s about. He’s a proven player but has come and shown that in this league, which isn’t always easy to do.
"But you can’t just focus on one man’s attributes because Arsenal have quality all over the team."
West Ham host Arsenal at 3pm this afternoon.