Calculate Tyre Size

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Have you ever wondered what the markings on the sidewall of your tyre mean? Your tyre’s sidewall markings are a tyre specification guide containing important information about size, load, and much more. This indicates the nominated tyre size for your vehicle from the manufacturer. Be careful if changing away from the nominated tyre size, as this could make your vehicle un-roadworthy.

Learn how to read tyre codes and your tyre size with the tyre size calculator.

Tyre size calculator, showing how to calculate your tyre size. Image of tyre calculator.
Vehicle placard tyre

Vehicle placard tyre size

Vehicle manufacturers will always provide tyre size information in the car user manual and also via a tyre placard fitted to your car. This will include information about the recommended tyre sizes, wheels and the correct tyre inflation pressure depending on vehicle use. The tyre placard is generally found inside the driver’s door opening, but sometimes found inside the fuel cap, glove box or under the bonnet. It is generally possible to fit aftermarket wheels and tyres of a different size, but it is important to consult a tyre professional before doing so to ensure the wheels and tyres meet local road regulations. A different inflation pressure may be needed in this case also.

How to find your tyre size?

Knowing how to check tyre size is straightforward. You can find your tyre size by examining the sidewall of the tyre, referencing your vehicle's owner's manual, or locating the placard inside the driver’s door jamb. Accurate tyre size ensures optimal performance, safety, and fuel efficiency.

If still uncertain about your tyre size, contact your local Bridgestone store who will be able to assist with all your tyre needs.

Select your tyre size

  • How to check your tyre size
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre profile size.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre width size.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre rim size.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre speed symbol.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre load speed.
    • Width

    • Profile

    • Rim

    • Load

    • Speed

    Tyre size calculator, showing how to calculate your tyre size. Image of tyre width size.
    Indicates the section width of a tyre in millimetres.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre profile.
    The sidewall height measured from the base of the tread to the rim. This number represents a percentage of the tread width. Low profile tyres have smaller aspect ratio percentages.
    Tyre size calculator, showing how to calculate your tyre size. Image of tyre rim size.
    Indicates the diameter of the wheel rim. So if you are buying wheels for existing tyres, this is the size in inches you will require.
    Load indicates the maximum load capacity at which a tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted and with the recommended inflation pressure. See table below for load index and the maximum load per tyre.

    Load index 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
    Max load/tyre (kg) 487 500 515 530 545 560 580 600 615 630 650 670 690 710 730 750 775
    Speed symbol is a code which indicates the speed at which a tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted and with the recommended inflation pressure. See table below for passenger tyre speed symbol ratings.

    Symbol E F G J K L M N P Q R S T U H V W Y Z
    Rating 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 240 270 300 240+

Tyre size explained

Tyre dimensions

Width:
The section width of your tyre in millimetres, from the inner sidewall to the outer sidewall. Example: 195mm

Aspect Ratio:
The height of your tyre from the base of the tread to the rim, as a percentage of the tread width. Low profile tyres have smaller aspect ratios. Example: The height of this tyre is 65% of its width.

Tyre Construction:
The method used to construct your tyre. Example: R, for radial ply construction. This is the most common method of construction for passenger tyres.

Rim:
The diameter of the wheel rim in inches. If you are buying wheels for existing tyres, this is the size you will need. Example: 15 inches.

Load Index and Speed Symbol
The maximum load capacity under which your tyre can safely operate, and at what speed. This is subject to the tyre being in sound condition, correctly fitted, and with the recommended inflation pressure. Example: 91 V

Tyre speed rating chart

Tyre speed symbol table

Speed symbol is a code which indicates the speed at which a tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted and with the recommended inflation pressure. See table below for passenger tyre speed symbol ratings.

 


Speed Symbol Rating (Km/h)
E 70
F 80
G 90
J 100
K 110
L 120
M 130
N 140
P 150
Q 160
R 170
S 180
T 190
U 200
H 210
V 240
W 270
Y 300
Z 240+

Tyre load rating chart

Tyre load index table

Load indicates the maximum load capacity at which a tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted and with the recommended inflation pressure. See table below for load index and the maximum load per tyre.


Load
Index
Max Load
(kg)
Load
Index
Max Load
(kg)
Load
Index
Max Load
(kg)
Load
Index
Max Load
(kg)
Load
Index
Max Load
(kg)
Load
Index
Max Load
(kg)
60 250 85 515 110 1060 135 2180 160 4500 185 9250
61 257 86 530 111 1090 136 2240 161 4625 186 9500
62 265 87 545 112 1120 137 2300 162 4750 187 9750
63 272 88 560 113 1150 138 2360 163 4875 188 10000
64 280 89 580 114 1180 139 2430 164 5000 189 10300
65 290 90 600 115 1215 140 2500 165 5150 190 10600
66 300 91 615 116 1250 141 2575 166 5300 191 10900
67 307 92 630 117 1285 142 2650 167 5450 192 11200
68 315 93 650 118 1320 143 2725 168 5600 193 11500
69 325 94 670 119 1360 144 2800 169 5800 194 11800
70 335 95 690 120 1400 145 2900 170 6000 195 12150
71 345 96 710 121 1450 146 3000 171 6150 196 12500
72 355 97 730 122 1500 147 3075 172 6300 197 12850
73 365 98 750 123 1550 148 3150 173 6500 198 13200
74 375 99 775 124 1600 149 3250 174 6700 199 13600
75 387 100 800 125 1650 150 3350 175 6900 200 14000
76 400 101 825 126 1700 151 3450 176 7100 201 14500
77 412 102 850 127 1750 152 3550 177 7300 202 15000
79 437 104 900 129 1850 154 3750 179 7750 204 16000
80 450 105 925 130 1900 155 3875 180 8000 205 16500
81 462 106 950 131 1950 156 4000 181 8250 206 17000
82 475 107 975 132 2000 157 4125 182 8500 207 17500
83 487 108 1000 133 2060 158 4250 183 8750 208 18000
84 500 109 1030 134 2120 159 4375 184 9000 209 18500

OD:
The overall diameter of your unloaded tyre in mm.

Type Definitions:
An abbreviation providing information about the type of your tyre.

Examples:
RFT – Run Flat Technology
MOE – Mercedes Original Equipment
LRR – Low Rolling Resistance
RBT – Raised Black Letters Tubeless
OWT – Outline White Letters Tubeless
RWT – Raised White Letters Tubeless
LWT – Line White Tubeless
TT – Tube Type
TL – Tubeless
XL – Extra Load
LT – Light Truck construction
N* - Porsche specification
☆ – BMW spec



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Vehicle data is provided by Vehicle Logic
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Vehicle data is provided by Vehicle Logic

Frequently asked questions

  • FAQs iconWhat tyre size should I choose for my car?

    We recommend you choose the tyre size identified by your car’s manufacturer on your vehicle tyre placard. Changing your tyre size from the manufacturer’s standard may mean your car is no longer roadworthy, and might not be covered by your insurance. Use our tyre size calculator to find the right tyre size for your vehicle.

  • FAQs iconHow do you determine which tyres fit my vehicle?

    We use your vehicle’s original tyre size to determine which tyres fit your vehicle. If you use our online tyre size calculator, it’s important that you enter your vehicle’s make, model, and year correctly. You may also search for tyres using your vehicle’s registration or tyre size.

  • FAQs iconWhat do the numbers on the sidewall of my tyre mean?

    The sidewall of your tyre is the part between the edge of the wheel and the tread. If you look closely at the sidewall, you will notice a series of numbers that give you important information about your tyre’s specifications.

    • Width
    • Aspect
    • Rim Size
    • Load
    • Speed
    The section width of your tyre in millimetres.
    The sidewall height measured from the base of the tread to the rim. This number represents a percentage of the tread width. Low profile tyres have smaller aspect ratio percentages.
    The diameter of the wheel rim in inches. This is the size you will need to choose if you are buying wheels for an existing tyre.
    The maximum load capacity at which your tyre can be safely operated. This is subject to your tyre being in sound condition, correctly fitted and inflated at the recommended pressure.
    A code indicating the speed at which your tyre can be safely operated. Again, this is subject to your tyre being in sound condition, correctly fitted and inflated at the recommended pressure.
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