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Radial or Crossply?

Crossply and radial tyres use different size markings.

Crossply tyres are measured in inches. The first number (7.00, for example) relates to the tread width (seven inches), the second number (16, for example) is the diameter of the wheel it fits (16 inches).

Radial tyres are measured in millimetres and inches. The first number (say, 185) is the tread width in millimetres. The two figures number after the forward slash (75, for example) relate to the sidewall profile of the tyre. The profile is a percentage of the width of the tyre. If no number is shown, then the tyre is 80 profile.

The ‘R’ before the next two numbers denotes the tyre is a radial, and the diameter of the wheel the tyre fits follows this.

You should aim to match the size of your new tyres with those recommended in your vehicle’s handbook — or we can check for you. The tyres on your vehicle now aren’t necessarily the correct size.

Where two figures and a letter are displayed together (ie 82 S) on both types of tyre, this is the load and speed rating. This is explained in more detail with reference charts lower down the page.

Speed / Load Ratings

The load and speed ratings on a tyre are displayed as a number (82, for example) and a single letter. These are deciphered for you in the tables below.

You should aim to match the load and speed ratings on your new tyres with those recommended in your vehicle’s handbook — or we can check for you. The tyres on your vehicle now aren’t necessarily the correct ones for it.

Tyre Speed Rating Table

This table shows the maximum speed a tyre is safely designed to travel at.

Speed Rating MPH KPH
N 87 140
P 93 150
Q 99 160
R 106 170
S 112 180
T 118 190
Speed Rating MPH KPH
U 124 200
H 130 210
V 149 240
Z 150+ 240+
W 168 270
Y 186 300
Tyre Load Rating Table
Load Index Load in KG
62 265
63 272
64 280
65 290
66 300
67 307
68 315
69 325
70 335
71 345
72 355
73 365
74 375
75 387
76 400
77 412
78 425
79 437
80 450
81 462
82 475
83 487
Load Index Load in KG
84 500
85 515
86 530
87 545
88 560
89 580
90 600
91 615
92 630
93 650
94 670
95 690
96 710
97 730
98 750
99 775
100 800
101 825
102 850
103 875
104 900
105 925
Load Index Load in KG
106 950
107 975
108 1000
109 1030
110 1060
111 1090
112 1120
113 1150
114 1180
115 1215
116 1250
117 1285
118 1320
119 1360
120 1400
121 1450
122 1500
123 1550
124 1600
125 1650
126 1700
Tyre Date Code Decoding
2000 to present
The date code is four digits long. The first two digits represent the week of production, and the second two represent the year. The tyre in the picture was made in the thirteenth week of 2011.
1990-1999
The date code is three digits long. For the Nineties this was followed by a triangle. The first two digits represent the week of production, the third digit represents the year. The tyre in the picture was made in the first week of 1996 (note the small triangle on the right).
1980-1989
The three-digit code was also used in the Eighties, but without the triangle. The format is otherwise exactly the same as the later system. So, the tyre in the picture was made in the seventh week of 1981.
Before 1980
If your tyre doesn’t have any of the markings above, it was made before 1980 and should be replaced as a matter of course.
Tyre Size Comparison
Current Wheel / Tyre
New Wheel / Tyre
Difference in circumference
mm (%)
Difference in diameter
mm
So when your speedo reads 70mph, you're actually travelling at
mph
Crossply to Radial Comparison

The title is a bit of a misnomer because no radial tyre is an exact-size replacement for a crossply. Crossply tyres have a sidewall profile that is between 95 and 100 per cent of the width of the tyre. The tallest profile you’ll find in a radial is 80 per cent.

So, radial tyres are always going to look smaller in the wheelarch than a crossply. That said, there are plenty of commonly-used radial replacements for crossply tyres, and these are shown in the table below. These aren’t specific recommendations, and if you are planning to swap from crossply to radial tyres, give our experienced team a call first on 01590 612261.

Radial tyres generally require higher pressures than crossply tyres. Again, our team can advise on car-specific pressures.

Crossply Radial 70% ratio Radial 80% ratio

520-10

165/70R10

145R10

520-12

165/70R12

145R12

550-12

175/70R15

155R12

560-12

175/70R12

155R12

520-13

165/70R13

145R13

560-13

175/70R13

155R13

590-13

185/70R13

165R13

600-13

185/70R13

165R13

640-13

175R13

670-13

205/70R13

185R13

700-13

205/70R13

185R13

520-14

145R14

560-14

175/70R14

155R14

590-14

185/70R14

165R14

600-14

185/70R14

165R14

650-14

195/70R14

175R14

700-14

205/70R14

185R14

750-14

215/70R14

195R14

800-14

225/70R14

205R14

850-14

235/70R14

215R14

900-14

245/70R14

225R14

950-14

500-15

145R15

560-15

175/70R15

155R15

590-15

185/70R15

165R15

600-15

185/70R15

165R15

640-15

205/70R15

185R15

650-15

195/70R15

185R15

200/70R15

185R15

205/70R15

185R15

670-15

215/70R15

195R15

710-15

225/70R15

205R15

760-15

235/70R15

215R15

800-15

245/70R15

225R15

820-15

235R15