Riders depend on their tires for a lot, so it’s crucial we make as informed a decision as possible when swapping out for new rubber. Knowing the basics is a good place to start, and is what we’re going to address here.
But its also important to take into account your ride style, the roads and conditions you’re likely to encounter and what characteristics you prize over others, things including mileage or wet weather performance. They will definitely have an impact on whether or not you’re satisfied with the tires you’ve chosen.
Knowing these can also help narrow down the search, since motorcycle tires are highly refined these days. An exemplary adventure-touring tire might fall well short if sport-touring is your game. Maybe you need something adept on road and track. You get the picture.
There’s some jargon tossed around unique to tires that’s helpful to know. This is by no means a complete list of all the words you might hear when talking shop about tires, but it’ll get you started.
Aspect Ratio: Section height/section width multiplied by 100. Expressed as a percentage.
Bead: The interior edge of the tire that fits to the rim. Inside is bead filler and bead wire, intended to maintain the stiffness of the bead area. The external portion of the bead is covered in a protective ply called a chafer, designed to keep the portion of tire in contact with the rim from becoming damaged by rubbing.
Carcass: The interior-most ply of the body of the tire. Steel or textile cords are utilized to provide both structure and support to the tire. The configuration of the layout determines whether tires are Bias, Bias Belted or Radial.
Compound: The collection of elements that comprise the tire tread. Usually some blend of synthetic rubber, carbon black, silica and other materials depending on intended use.
Contact Patch: The portion of rubber that is in contact with the road.
Diameter: Interior diameter, or diameter of the rim.
DOT: Department of Transportation. Motorcycle tires in the United States must be compliant with DOT standards to use on public roads.
Load Index or Load Rating: Maximum load carrying capacity at maximum pressure – check chart for conversion to pounds/kilograms.
Inner Liner or Tubeless Liner: Many motorcycle tires are tubeless and include a specialized rubber lining inside the carcass.
Ply: Internal layer of a tire.
Section Height: Measurement from the bottom of the bead to the top of the tread.
Section Width: Measurement from the outside of one sidewall to the other.
Sidewall: The portion of the exterior of the tire that extends from the rim to the tread shoulder.
Speed Index or Speed Rating: Maximum speed under recommended load capacity – check chart for conversion to mph/kmH.
Tread: The rubber exterior portion of the tire built for contact with the road. It’s contributes to a tire’s grip on the road, affects the handling characteristics and can contribute to the longevity of the tire.
Tread Pattern: Grooves built into the tread of the tire, designed to improve handling in wet and/or low grip conditions.
Motorcycle tire size is fundamental because bikes generally work best with the manufacturer’s intended tire size. There are occasions when a tire that is not the factory-recommended size can be used, but we suggest sticking to the manufacturer’s specs. That way you ensure proper clearances between components, optimal handing and appropriate load and speed ratings for the build of your bike.
Three designations exist that you might encounter regarding tire size – Metric, Alphabetical and Inch. Below is a brief outline of each.
Metric – 180/55R-17 (73W)
180 – Width (in millimeters)
55 – Aspect Ratio (%)
R – Construction (R-Radial; B-Bias Belted; No Letter – Bias)
17 – Rim Diameter (in inches)
73 – Load Index (pounds or kilograms)
W – Speed Rating (mph or kmH)
Alphabetical – MT90B-16 (74H)
M – Motorcycle Code (Simply indicating the tire is built for a motorcycle)
T – Tire Width Code (Letters represent inch measurements – check chart for conversion)
90 – Aspect Ratio (%)
B – Construction (R-Radial; B-Bias Belted; No Letter – Bias)
16 – Rim Diameter (in inches)
74 – Load Index (pounds or kilograms)
H – Speed Rating (mph or kmH)
Inch – 3.00/21 4PR
3.00 – Section Width (in inches)
21 – Rim Diameter (in inches)
4PR – Casing Strength (Ply Rating)
Bias Belted: A Bias Belted tire utilizes ply cords that extend diagonally from bead to bead relative to the centerline and a stabilizer belt across the width of the tire.
Advantages: This type of tire provides a smooth ride that is similar to the bias tire, but lessens rolling resistance due to belts increasing tread stiffness. The plies and belts are at different angles, which improves performance that compare to non-belted bias tires.
Bias: Bias tires typically have the ply cords that extend diagonally from bead to bead at a range of 30 to 60 degree angles from the centerline. Each successive ply is laid at an opposing angle, forming a criss-cross pattern.
Advantages: The design allows the entire tire body to flex easily, giving a comfortable ride on rough surfaces.
Radial: Radial constructed tires utilize both ply and breaker (or belt) cords. The ply cords extend from bead to bead at approximately 90-degree angle to the centerline of the tire. The breaker (or belt) cords are placed on top of the ply cords across the width of the tire.
Advantages: Adding breaker (or belt) cords results in a stiffer carcass which helps provide a longer tread and tire life, better steering control and handling, overall smoother ride and ride comfort, and higher tread puncture resistance.
Load and Speed Ratings
The load rating indicates the maximum weight that can be carried safely by the tire when inflated to the maximum recommended air pressure. Take this one seriously and don’t overload your tires!
The speed rating is the maximum speed the manufacturer determines a tire can manage when at its load capacity.
Motorcycle tires, when properly stored and cared for, have a long service life. When stored properly, tires from 5-7 years old can retain all the chemical and physical properties of a brand new tire. Most manufacturers recommend tires 10 years or older be replaced by a new set, regardless of storage or usage circumstances.
The production date is found on the tire sidewall at the end of series of letters and numbers starting with DOT. Tires produced after 1999 utilize a code in which the final four digits of this series provide a week and year of production. For example, 1916 is the 19th week of 2016.
Tires need to be stored in clean and dry environment that is dark and well ventilated. If tires are on the rim and stacked, they need to be restacked every four weeks. Hanging tires that are on rims is preferred. Tires without rims must not be stacked or hung up, but stored standing upright and rotated every four weeks. This is to ensure the tires retain their original shape.
Numerous other issues can affect the life of a stored tire, from chemicals stored in the vicinity, light or temperature fluctuations and the like.
All tires need to be checked regularly. For tires in use, tread depth should not be less than 2mm. There should be no cracks or deformities in the tire and valve-stems need to be in good condition. Rims need to be in good condition as well.
Riders Domain recommends that all tires be inflated to the manufacturer’s recommended tire pressure for the expected conditions and loads. Tire pressures should be measured when the tires are cold before every ride.
When you get a set of new tires, know that the external surface will be quite smooth owing to the mold-releasing agent used during manufacturing. It’s recommended that riders avoid sudden braking and extreme lean angles during the first 100 miles or so, until the surface is sufficiently scrubbed-in.
Some Frequently Asked Questions
What is the difference between Bias and Radial?
Refer to the “Construction Section” for a more detailed answer. But it’s basically a difference between the construction of the structural cords inside. Bias tires tend to be more flexible and Radial tires are more stiff.
What does the number in the parenthesis mean example (71V)?
The number (71) refers to a tire’s load index and the letter (V) is its speed rating. In this case the 71 refers to a 761-pound load index and the V indicates the tire is capable of a maximum speed of 149+mph under recommended load capacity.
How old is too old for a tire?
It depends on how the tire was stored, but tires can be good as new 5-7 years after production from a chemical and physical property standpoint. Most manufacturers recommend replacement after 10 years, regardless of storage. Be sure to check for any irregularities in the shape and condition of an older tire before you mount.
Can I mix and match tires?
We wouldn’t recommend getting too wild with mixing and matching. Different compounds, profiles, tread patterns and construction all contribute to a tire’s, and ultimately a bike’s, performance. Handling characteristics can be adversely affected if there’s a big disparity between the front and rear tire. We’d rather you have the best ride possible and that’s most likely to happen using tires that were designed to work together.
How do I read the date code?
You want to look at the final four digits of the string of numbers and letters which start with DOT. Those for digits correspond to the week and year of production. So a 2517 was produced the 25th week of 2017.
Why doesn’t the manufacturer make white walls for my bike?
White walls are a style choice and require some special manufacturing processes to create. From a cost benefit point of view, why would a brand invest the extra bit of time and resources into making a tire that may only sell a handful of units when they could be focusing on those products that have broader appeal and more certainty in the market? Unfortunately, that makes it tough for those that do want to sport a set of white walls, but until the entire model year range of Harley-Davidson’s come equipped with ‘em, things probably won’t be changing anytime soon.
What’s the best tire on the market for my bike?
Today or tomorrow? The difficult thing about a question like this is that tire manufacturers release improvements every few years, so the “best” tire on the market for your particular bike might be one thing one day, and another the next.
Looking further, qualifying something as “best” requires a lot of input from you as a rider. Bikes can be really versatile, think of something like the V-Strom 650. Are you planning to get deep into the backwoods, or are you looking for something built to withstand a lot of freeway miles? Do you ride all year, regardless of condition? Do you want something transferrable from the street to the track? Narrow down the field a bit by knowing what kinds of abuse you’ll be subjecting the tire to.
If you get a few of these answered, we can definitely point you in the right direction.
Why don’t motorcycle tires have mileage ratings?
Because tire life depends largely on use and care. If you ride hard, overload the capacity of the tire or don’t check pressures regularly, wear can increase. If you toss on a new set of tires and leave your bike out in the barn for two years, irregularities and deformities can occur. Some manufacturers offer coverage up to certain mileage marks, with caveats of course.
The bottom line is that too many factors specific to a rider’s habits on the road, or lack thereof, contribute to a tire’s mileage capabilities for manufacturers to set a specific number.
Can I buy an extended warranty?
Not typically. It all depends on the manufacturer, but most just offer standard, limited coverage. Remember to keep your receipts!