Alfa Romeo 166 Booklet page 250

CORRECT TYRE READING
Below are the instructions necessary to know the meaning of
the code stamped on the tyre.
The code may be like one of the examples given below.
Example:
225/45 R 17 91 Y
225/45 ZR 17
225 = Nominal width (distance in mm between the sides).
45 = Percentage height/width ratio.
R = Radial tyre.
ZR = Radial tyre with speed above 240 kph.
17 = Rim diameter in inches.
91 = Load (capacity) index, e.g. 91 = 600 kg. Not present in
ZR tyres.
Y, Z = Maximum speed index. In ZR tyres the speed index Z is
before the R.
250
or
Load index (capacity)
60 = 250 kg
61 = 257 kg
62 = 265 kg
63 = 272 kg
64 = 280 kg
65 = 290 kg
66 = 300 kg
67 = 307 kg
68 = 315 kg
69 = 325 kg
70 = 335 kg
71 = 345 kg
72 = 355 kg
73 = 365 kg
74 = 375 kg
75 = 387 kg
76 = 400 kg
77 = 412 kg
78 = 425 kg
79 = 437 kg
80 = 450 kg
81 = 462 kg
82 = 475 kg
83 = 487 kg
84 = 500 kg
85 = 515 kg
86 = 530 kg
87 = 545 kg
88 = 560 kg
89 = 580 kg
90 = 600 kg
91 = 615 kg
92 = 630 kg
93 = 650 kg
94 = 670 kg
95 = 690 kg
96 = 710 kg
97 = 730 kg
98 = 750 kg
99 = 775 kg
100 = 800 kg
101 = 825 kg
102 = 850 kg
103 = 875 kg
104 = 900 kg
105 = 925 kg
106 = 950 kg