Donk-overbets on the river... do we always call them in these spots?

[K䲰䮥n]

Villain is reg TAG. 17/12/2.5. Hasnt gone "creative" vs me before. Hero's image is TAG.

NL100 6max, 6 players, 110BBs stacks.
3 fold
Hero raises to $3.50 with K[img]/images/graemlins/spade.gif[/img] K[img]/images/graemlins/diamond.gif[/img]
SB calls
BB folds

Flop: 4[img]/images/graemlins/club.gif[/img] 6[img]/images/graemlins/heart.gif[/img] 8[img]/images/graemlins/spade.gif[/img]
Hero bets $7
SB calls

Turn: J[img]/images/graemlins/diamond.gif[/img]
Hero bets $15
SB calls

River: 8[img]/images/graemlins/diamond.gif[/img] (pot $52)
SB bets $85
Hero calls