Wheels and Tires
Wheels and Tires...rubber is rubber right? Not quite. The tire is the one thing that is between your bike and the road. Choosing the rite tire is very important, not just to your bike, but to you. Tires equal handling. Know your bike and what kit needs. NEVER downgrade from one tire to another.
Part of knowing your what kind of tire you will need is knowing how to read the size and speed rating. Here are the main sizing systems for motorcycle tires:
Inch system (square): example 3.00-21
In order for a tire to be considered "square", the first number (3.00) must be divisable by 25. Here in this example the "3.00" represents the cross sectional height AND width of the tire in inches. The "21" represents the rim diameter in inches.
Inch system (low profile tires) example: 4.10-19
In this example the "4" represents the cross sectional width of the tire in inches. The ".10" means that the cross sectional height is 10% less then the cross sectional width of the tire (4) in inches
Alphanumeric system example: MH90-21
In this example, you need to know the manufacturer of the tire and have the manufacturer chart in order to read the size. The "M" stands for motorcycle tire and the "H" stands for cross sectional width of the tire. This is where you will need to look at the manufacturer chart. the "90" represents the aspect ratio. So say the "H" is the symbol for 2.5 inches, then the cross sectional height of the tire is 90% of 2.5 inches . And like previous examples, the "21" represents the rim diameter in inches.
Metric system example: 120/70-17
In this example the "120" represents the cross sectional width of the tire in millimeters (120mm). The "70" represents the aspect ratio, so the cross sectional height is 70% of 120mm. The last number, "17" represents the rim diameter in inches.
Something to also consider about tires is the types that are made. You have bias ply, bias belted and radial.
Bias ply tires are made with plies or cords that run at an angle from bead to bead. These plies can be made of nylon, rayon or polyester. These tires were used in the mid 70's and are still used today mainly for off-road use. The way to identify this type of tire is to look for a dash (-) in the sizing index. Examples: 3.00-21 or MT90-17 or 190/60-17
Bias belted tires are the same construction as bias ply tires, but they have added belts that run the circumference of the tire. On these tires the belts can be made of Kevlar, fiberglass, or steel. The way to identify a bias belted tire is to look for the "B" in the sizing index. Examples: 3.00B21 or MT90B16 or 190/60B17.
Radial tires have plies that run straight from bead to bead and they have a very stable contact patch. The plies can be made of Kevlar, fiberglass or steel. The sidewalls are shorter to regain stiffness and these are the only type of tire with a "Z" and higher speed rating. The way to identify radial tires is to look for the "R" in the sizing index. Examples: MT90R16 or 190/60R17
Speed ratings determine what each type of tire can handle. Here are the speed ratings and where to find them.
S-112 mph
U-124 mph
H-130 mph
V-149 mph
Z-149 + mph
W-168 + mph
Y-188 mph
Here is another example:
Inch System: 5.00H164PR The "H" is the speed rating
Metric System: 130/90-16 67 H The "H" is the speed rating and the "67" is the load index
