Maybe this will be useful to you :

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A typical tyre has markings such as 185/60R14 82H. This translates into the following :
185 - Width : The first three digits of a tyre size is the width of a tyres footprint on the road surface in millimetres.
60 - Section Height/Width % (Aspect Ratio) : These digits represent the Aspect Ratio. Profile is tied in with Aspect Ratio. An aspect ratio of 60 means the height of the tyre is 60% as high as it is wide. Section height is the size in m
R - Stands for Radial-ply Construction. Most car tyres are radial-plies for durability, road-holding and high performance. Trucks and commercial vehicles have cross-ply tyres which are cheaper and can be re-threaded, but are unstable at high speed.
14 - Rim Size/Diameter : Measured in inches, this is the size of steel or aluminium rim that the tyre fits around. Sizes start from 10 inches of a Mini to 17 or 19 inches on typical Max Power cover car !
82H - Load Index & Speed Rating : T-rated tyres can handle speeds up to 190 km/h. H-rated tyres can handle speeds up to 210 km/h. V-rated tyres can handle speeds up to 240 km/h

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;-)

Raghu