Many of you will have noticed a bunch of numbers and letters printed alongside your motorcycle’s tires. Most of you don’t really care what they mean, even if they mean anything since you’ll suppose that the motorcycle manufacturer knew what he was doing when the tires were installed.
But if you ever need to change the tires and can’t find the exact same ones, it’s good to know what they mean. Especially since those numbers and letters will impact your safety while riding. Why? Because they indicate among other what the maximum speed of the tire is allowed to be. So maybe your motorcycle can ride at 200 mph, if your tire is rated for 100 mph, you are in trouble. The same applies for carrying a pillion, cargo and even towing a trailer.
The tire number is represented in one of three different ways, depending on where the tire is made and sold.
It looks like this: 180/55ZR-17 M/C: Tire width, “/”, Aspect ratio, Speed Rating”, Tire Construction, “-” Rim diameter, Motorcycle Tire.
5.00H-16 APR: Width, Speed Rating, Rim Diameter, Casing Strength
MT90S-16 : Motorcycle Tire, Width code, Aspect Ratio, Speed Rating, Rim Diameter,
The figure is expressed in millimeters or inches and represents the width from the outer wall to outer wall of the tire.
This means the tire’s cross-sectional profile a represents the percentage of the height to width ratio. 90 for example means 90%
The speed the tires are rated at is indicated with a letter:
F – 50 mph
H – 130 mph
J – 62 mph
K – 68 mph
L – 75 mph
M – 81 mph
N – 87 mph
P – 93 mph
Q – 99 mph
R – 106 mph
S – 112 mph
T – 118 mph
U – 124 mph
V – 149 mph
W – 168 mph
Y – 186 mph
Z – 149+ mph
As you can see, the numbers and letters are not exactly sequential, but that is because of historical reasons. Letter type Z is old, and shows that the tire is capable of above 149 mph, which is also the case of W and Y types. There are also some letters missing in the lineup.
WARNING: Do check the tire manufacturer’s rating, since some differ.
The letter indicates the whether the tire is Belted (code B) or Radial (code R).
As the word says, it’s the diameter of the wheels rim on which the tire is mounted, expressed in millimeters or inches.
Tire Load Index
The tire numbers also indicate how much weight they can carry. This is important when carrying pillion and cargo. Too much weight will deflate or worse, burst your tire.
The Load Index (L.I.) is a bit long to display here, but best is to go to the tire manufacturer’s web site and find out what the maximum load is for your tires. Believe me, it’s important especially if you have changed brand.