Andy W
Active Member
Two interesting sites about tyres and sizing wheels to wheel wells on kit cars. Makes interesting reading.
http://www.kitcarbooks.com/tiretech.html
http://www.usedtyreexports.com/tyres_tyre_facts.htm
understanding tire sizing:
Let's spend a moment deciphering the code on the side of a tire; a P225/60VR15 for example. Just what does all this mean?
P - stands for passenger car.
225 - stands the tire width in millimeters.
60 - indicates the height of the side wall relative to the width, known as the aspect ratio. In this case, tire height is 60 percent of the width.
V - is the speed rating (Z = 149 + mph rating, V = up to 149 mph, H = up to 130 mph-, U = up to 124 mph, T = up to 118 mph and S = up to 112 mph).
R - stands for radial.
15 - is the wheel size needed for this tire, in inches
If you use the following formula, you can figure the diameter and width of a tire from its sidewall markings. Multiply the tire width (225 mm in this case), by the conversion factor (.03937), multiply that by the aspect ratio (.60), multiply by 2, and add the rim diameter (15). If I've done my work correctly, that should yield for you the overall tire diameter and width in inches.
In this case a P225VR15 works out to be about 25 5/8" in diameter by 9 1/5" wide with a speed rating of up to 149 mph.
http://www.kitcarbooks.com/tiretech.html
http://www.usedtyreexports.com/tyres_tyre_facts.htm
understanding tire sizing:
Let's spend a moment deciphering the code on the side of a tire; a P225/60VR15 for example. Just what does all this mean?
P - stands for passenger car.
225 - stands the tire width in millimeters.
60 - indicates the height of the side wall relative to the width, known as the aspect ratio. In this case, tire height is 60 percent of the width.
V - is the speed rating (Z = 149 + mph rating, V = up to 149 mph, H = up to 130 mph-, U = up to 124 mph, T = up to 118 mph and S = up to 112 mph).
R - stands for radial.
15 - is the wheel size needed for this tire, in inches
If you use the following formula, you can figure the diameter and width of a tire from its sidewall markings. Multiply the tire width (225 mm in this case), by the conversion factor (.03937), multiply that by the aspect ratio (.60), multiply by 2, and add the rim diameter (15). If I've done my work correctly, that should yield for you the overall tire diameter and width in inches.
In this case a P225VR15 works out to be about 25 5/8" in diameter by 9 1/5" wide with a speed rating of up to 149 mph.
