Mercedes-Benz 2015 GLK Operator's Manual page 366

Wheel and tire combinations
364
R20
Tires
BA: 235/45 R20 100 H XL M+S
All-terrain tires
R17
Tires
BA: 235/60 R17 102 H M+S
Winter tires
R17
Tires
BA: 235/60 R17 102 H M+Si
R19
Tires
BA: 235/50 R 19 99 H M+S i
GLK 350 4MATIC
Summer tires
R19
Tires
FA: 235/50 R 19 99 V
RA: 255/45 R 19 100 V
Use of snow chains not permitted. Observe the notes in the "Snow chains" section.
14
14
Alloy wheels
BA: 8.0 J x 20 H2
Wheel offset: 1.65 in (42 mm)
Alloy wheels
BA: 7.5 J x 17 H2
Wheel offset: 1.87 in (47.5 mm)
Alloy wheels
BA: 7.5 J x 17 H2
Wheel offset: 1.87 in (47.5 mm)
Alloy wheels
BA: 7.5 J x 19 H2
Wheel offset: 1.85 in (47 mm)
Alloy wheels
FA: 7.5 J x 19 H2
Wheel offset: 1.85 in (47 mm)
RA: 8.5 J x 19 H2
Wheel offset: 2.05 in (52 mm)