How To Read A Motorcycle Tire
It's a rotten feeling. You look down at your tire, and there's no
denying that those nice deep grooves have become a shadow of their
former selves. It's a goner, and it's getting worse with every mile.
As you look around your local motorcycle shop for a new tire, you
see all sorts of letters and words on the sidewalls. Would you believe
just about everything you need to know about a tire, including when it
was made, is contained there?
It's really not that difficult to decipher the black art of tire
designations, and knowing what you've got makes you a well-educated
consumer-which is never a bad thing.
First off, there's those big numbers and letters that may read
something like 130/90 16, or MT90 16. These numbers indicate the size
of the tire, and the rim it's designed to go on. In this case, these
are both the same size tires.
How can we tell?
Let's start with the first series of numbers, 130/90 16, otherwise
known as the metric designation. This is the most popular nomenclature
today and it's practically a standard in the automotive world.
130 designates the tire's width in millimeters, measured in a straight
line through the tire from one edge of the tire's tread to the other.
The second number, 90, is a bit trickier to understand. This represents
the aspect ratio between the tire's width and its height, or how tall a
tire is in relationship to its width. Simply put, the higher this
number is, the taller the tire will be. In this case, the tire is 90
percent as tall as its width, or 117mm.
The last number, 16, is the tire's rim diameter expressed in inches.
The width on some tires may be expressed in inches as well, but usually the aspect ratio is left off.
The other series of numbers and letters, MT90 16, represents the
same tire size, but it's expressed in an alphabetical code. M means the
tire is designated for motorcycle use, T is the tire width code, 90 is
the aspect ratio and 16 is the rim diameter.
Size conversion chart
|Front tires ||Rear tires |
|Metric ||Alphanumeric ||Metric ||Alphanumeric |
|80/90 ||MH90 ||110/90 ||MN90 |
|90/90 ||MJ90 ||120/80 ||MP85 |
|100/90 ||MM90 ||120/90 ||MP85 |
|110/90 ||MN90 ||130/90 ||MT90 |
|120/90 ||MR90 ||140/90 ||MU90 |
|130/90 ||MT90 ||150/80 ||MV85 |
|150/90 ||MV85 |
The alpha numeric system is the older method for tire sizing. And in
the old days, tires just didn't get much bigger than an MV85, which
corresponds to a 150mm width. Therefore, newer tires larger than 150mm
will only carry the metric sizing designation
Speed and construction
Interspersed with these sizing numbers, you're likely to find other
letters that'll appear as such: 160/70VR 16, 170/60R 16V, or in other
combinations. These two extra letters indicate speed rating and tire
Each letter in the speed rating notes the maximum speed a tire can
sustain under its recommended load capacity. For instance, V is
equivalent to a maximum speed of 149 mph. Because this rating system
was created in Europe, the increments per letter are in 10 kilometers
|Rating ||Speed: miles per hour ||Speed: kilometers per hour |
|Q ||99 mph ||160 km/h |
|S ||112 mph ||180 km/h |
|T ||118 mph ||190 km/h |
|U ||124 mph ||200 km/h |
|H ||130 mph ||210 km/h |
|V ||149 mph ||240 km/h |
|W ||168 mph ||270 km/h |
|Y ||186 mph ||300 km/h |
|Z ||Over 149 mph ||Over 240 km/h |
The next letter, R, indicates the construction used within the
tire's casing. R stands for radial construction and B means belted bias.
Load and pressure codes
The next number or letter you may encounter, after the tire size, is
the load index. This is the weight the tire is capable of handling when
properly inflated. It's usually expressed in either a numerical code,
or a letter code. Most manufacturers will also spell out on the
sidewall what that maximum load is so there's no guessing—you'll find
it usually listed with the tire's maximum air pressure.
It's good to note here that you should only fill a tire to the
motorcycle manufacturer's recommended level. Besides under inflation,
one of the biggest mistakes people make with their tires is to overfill
them to the maximum level indicated on the sidewall. This leads to poor
handling and premature wear. If in doubt, either consult your owner's
manual, contact your local dealer, or go to the tire manufacturer's
website. Most include the recommended pressure for each motorcycle,
along with other tire options. And be sure to measure pressure when the
tire is cold. Measuring hot will skew the numbers.
Rotation and balance marks
One of the more critical marks on a motorcycle tire is the rotation
arrow, or arrows. Today's specialized tires generally have a tread
pattern that must go in only one direction. Some manufacturers even
state that their tread patterns are designed to disperse water, and by
mounting the tire backwards, they won't work.
The other big reason for noting wheel direction has to do with the
manufacturing process. The tread rubber is initially a flat strip
that's cut to length, at an angle, and then spliced together with the
two ends overlapping, creating a hoop. Under acceleration, a tire
mounted backwards will try to peel back this splice. The opposite is
true for the front wheel, where directional forces are reversed under
Another mark to look for when mounting a tire is a painted balance
dot, or dots. Most tires are pre-balanced by the manufacturer. They
will then put a mark on the tire indicating where the valve stem should
Born on date, and wear's the tread?
Other useful information on the tire's sidewall includes its
manufacturing date. Look on the side for a raised block with four
digits; it's usually next to the U.S. DOT tire identification number.
The first two indicate the week of its manufacture, and the last two
are for the year. For example, 1702 would indicate the tire was
manufactured in April, 2002. Prior to 2000, there were only three
digits, with the last one indicating the year.
tires may have raised triangles, or the letters TWI, to show where the
tire wear indicators are in the tread. When these marks are equal to
the tread, it's time for new tires.
Other information on the sidewall is usually spelled out; "tubeless"
or "tube type" may be substituted with the letters TL or TT
respectively, and the tire ply, composition and materials used may also
be spelled out.
Now you know all you need to know to have an intimate conversation with the black hoops around your rims.