Centres Jamie Roberts (1.93m, 110kg) and Jonathan Davies (1.86m, 104kg) and wings George North (1.94m, 109kg) and Alex Cuthbert (1.98m, 104 kg) are all powerfully built players, something Meyer has taken note of.
"Wales will be well prepared," Meyer told SAPA.
"They are a quality side with big backs, which will give them good (go) forward ball.
"They also played together in the Six Nations, while we are just starting out.
"We need a big step up in our work."
The Boks also have injury concerns at centre with captain Jean de Villiers and Jaque Fourie missing, which saw Frans Steyn and JP Pietersen start in midfield in the 47-13 win against the World XV on Saturday.
Wales coach Warren Gatland views this as an area the tourists could expose.
He told the Wales Online website the loss of De Villiers's experience and leadership would be big for the Boks.
“He has always been a big thorn in our side, he marshals the defence and scored a lot of tries."
Wales will face the EP Kings in Port Elizabeth on Tuesday night, before tackling the Boks in back-to-back Tests (Durban, June 14 and Nelspruit, June 21).