Wheel and tire sizes
To assure correct fitment, accurate replacement wheel size, dimension and load-carrying capacity are serious. Always consult the wheel manufacturer/distributor’s literature to confirm that the desired wheel and tire combination is an up to standard application for the vehicle. Using tires of different sizes may also cause damage to your vehicle. Be sure to use the same size and type tires on all wheels. According to RMA guidelines, there is risk in installing a tire of one rim diameter on a rim of a different rim diameter. Always replace a tire on a rim with another tire of just the same rim diameter designation and suffix letters.
The following are various high performance wheel and tire measurements that play an important part in determining tire and wheel fitment and sizes:
Wheel Backspace
Wheel Offset
Bolt Circle
Hub-Centricity vs. Lug-Centricity
UTQG (Uniform Tire Quality Grading) labeling system
Calculating Tire Dimensions
Tire’s sidewall
Being able to read and comprehend the information printed on a tire’s sidewall will make it easier for you to comprehend your tires and assist you in choosing a replacement set. One of the most significant facts for wheel and tire is width.
Width is significant to assuring customer satisfaction and pleasure. Besides correct fitment, width of wheel and tire also influences handling and ride quality. Always choose a rim width within the range of the tire’s acceptable rim width specifications. A wider rim raises vehicular stability, steering response and cornering ability. A rule of thumb is to use a rim width 90% as wide as the tread width (not section width) of a performance tire for street applications. This provides an excellent balance between performance and ride quality. Always be sure that the chosen rim width is within the tire’s range of acceptable rim width specifications. A narrow rim would result in an improvement in ride quality, but may forgo the tire’s ultimate performance capabilities. A mid-range rim width provides a balance between handling capabilities and ride quality. An example of a proper application would be to use a 15″ x 6″ wheel for a 205/70VR15 tire. Never try to mix mill metric wheels and tires with standard inch wheels and tires. An improper application would be mounting a 200/60R390 size tire on any 15″ wheel.
A 390mm tire is designed to fit on a wheel with a diameter of approximately 15.35″ with a non-standard bead seat. Reading your tire’s sidewall is a must anytime tires are mounted on wheels. Always keep in mind that a proper and accurate size of the wheels and tires develop both the performance and look of your vehicle and your life depends on a few square inches of rubber when you drive your car or truck.