Choosing the Right Wheel Size
This is not as "tuff" as you think. The size on the tire tells you all you really need to know.
Lets take a tire size of 10 x 4.50 x 5. - The 10 stands for the diameter of the tire which is 10 inches.
The 4.50 stands for the suggested width of the rim that the tire will mount to which is 4.5 inches wide.
The last number 5 is the wheels diameter that the tire will mount on, in this case it is a 5 inch wheel.
(In kart racing, especially oval racing, you would usually mount your wheels wider then your tires suggested. 1 to 2 inches is normal)
The difference between USA Mount Wheels and Metric Wheels:
USA Measurements = A 2.125", B 1.75", 1/4" Stud Hole
Metric - A 50mm (2"), B 40mm (1.5"), 8mm Stud Hole
Reading Wheel Sizes:
Following each part number will be a description that might look like this:
8X8 3B+5N 4/110 .125 10MM
The first number refers to the wheel diameter, measured from the tire bead seat.
The second number refers to the wheel width, measured from the inside bead to inside bead.
The third number refers to the width of the inside half of the wheel, in this case in a BELL shape.
The fourth number refers to the width of the outside half of the wheel, in this case in a NOSE shape.
This 4/110 refers to the bolt pattern. It has 4 bolt holes, equally spaced around a 110 millimeter diameter circle.
This .125 refers to the thickness of the material used in the wheels, in this case .125 in. thick.
This 10MM refers to the size of the bolt hole, in this case 10 millimeters.
B = Bell Shaped N = Nose Shaped