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Choosing the Right Motorcycle Tire: Size, Load Ratings, Speed Ratings and More

Posted on July 20, 2018 by Motorcycle Maniac.

Three Motorcycle Tires Shown on Road

Chaparral Motorsports has all kinds of motorcycle tires!  We have hard compound, soft compound, intermediate compounds. Wide White Wall, Narrow White Wall, super sticky tires and high mileage tires, 100% street tires, 100% dirt tires and everything in between 80/20, 70/30, and even 50/50. But none of that matters if you don’t know what motorcycle tire fits your bike.  Fitment isn’t just about size, there are several other factors to consider, so lets dive in. But first if you're the type of person that would rather watch the move than read the book check out this video on our YouTube channel which covers everything below.

Tire Diagram

How to Read Motorcycle Tire Size

This is the first place to start, and then we will drill down into the specifics.  Having talked one-on-one with thousands of customers, the reality is that most people don’t know what size tires their bikes are running. How do you find your bikes tire size?  There are three common size formats for street tires: Metric Sizing (Most Common) , Alpha Numeric (Mostly Cruiser) and Inch Sizing (Mostly Dirt Bike)

  1. Get on the ground and look. If your bike is running aftermarket wheels, the actual tire size might be different than what is listed in your owner’s manual or on the spec sticker on your motorcycle.
  2. If you know your bike is 100% stock, you can check your owner’s manual or an on-line data spec sheet.

Metric Tire Sizes:  (Most Common Motorcycle Tire Format)

180/70R-16  :  This is the number that you are looking for.

  • The first number (180) is the width of the tire in millimeters.
  • The second number (70) is the aspect ratio, which is the height of the sidewall. The height is 70% of the width or 126mm high.
  • The third number (16) is the rim size. In this case, the rim size is 16 Inches in diameter.
  • The letter between the second and third numbers, either R or B will tell if you if the tire is Bias Ply or Radial. If there is no letter, the tire is Bias Ply.

Alpha Numeric Motorcycle Tire Sizes: 

MU85B16  :  This is the Alpha/Numeric sequence you are looking for.

  • The first set of letters is the width. MU = 140 millimeters. Reference a Street Tire Size Conversion Chart for all of the Letter Designation Breakdowns.
  • Next letter will be B or R for Bias Ply or Radial
  • The Last number will be the rim size or rim diameter.

Numeric : (Mostly Dirt Bike, Vintage or Sidecar)

5.00-16 : This is the number you are looking for.

  • The first number (5.00) is the tire width in inches. 5.10 = 127 millimeters
  • The second number is the rim size or rim diameter which in this case is 16 Inches.
  • Numeric tire sizes typically run from 2.75 or 80mm or MH all the way to 6.0 or 150mm or MV.  See a Street Tire Conversion Chart to see all of the sizes in between. Detailed Tire Diagram

Radial vs. Bias Ply

Bias Ply tires were the original and they are best suited for heavy duty loads, and that is why we see them on most heavy cruiser and touring motorcycle applications. Bias Ply tires are made of layers of cords laid down from bead to bead running across the tire in alternating layers made up of materials such as Nylon, Rayon or Polyester. This makes for a very stiff sidewall, which will bear much weight, but the tires get hot, and are less nimble than their newer Radial brothers and sisters.

Radial Tires, which came to the motorcycle world in very limited applications in the 1980’s, run their layers across the tire radially and are typically made of steel. These alternating layers of steel belts are stacked in the tread area of the tire only. Steel belts dissipate heat quicker than bias cords and the sidewalls of radial tires are thinner and more flexible allowing the tire to be more nimble and provide more rider feedback than a Bias Ply tire.

Motorcycle Tire Size Chart

Motorcycle Tire Load Rating

The next series of numbers and letters (77H) will be the speed rating and load index of the tire. This code is presented the same for either Metric or Alpha/Numeric tires. Just because the “tire size” is the same size that your wheel or rim will “accept” does not mean that that tire is a good fit for your motorcycle or  your riding style. Check it out…

  • The numbers (77) represent the load carrying capacity of the tire. In this case, 77 means 908 pounds. A typical load rating chart shows 47 or 386 lbs all the way up to 87 or 1,202 lbs.
  • The letters (H) represent the speed rating of the tire. In this case, H means a top speed of 130 miles per hour. A typical speed chart will show J or 62mph all the way to W which is 168mph.
  • Now… sometimes we will see a ZR in the tire size and then a different Load Rating / Speed Index label to follow. This Z indicates a maximum sustained speed capability in excess of 149 mph and the 91W indicates a 168mph Maximum Top Speed.

Motorcycle Tire Speed Rating

Speed ratings are as follows:

J 62mph
K 68mph
L 75mph
M 81mph
N 87mph
P 93mph
Q 99mph
R 106mph
S 112mph
T 118mph
U 124mph
H 130mph
V 149mph
W 168mph
Y 186mph
Z/ZR 149+mph

It is very important that you choose a tire for your vehicle that meets or exceeds your vehicles load or your riding style. Just because a tire is the right size and is cheap… does not mean that it will be able to “carry the load” you will throw at it or be able to “sustain the speeds you travel.”  Load rating and speed ratings are often overlooked when consumers are choosing tires. If running tire that does not meet your vehicle needs or your riding style can lead to premature tire wear or even tire failure. Bottom line, it is Dangerous! Don’t do it.

Can You Put Wider Tires On Your Motorcycle?

Going wider or or narrower than your bikes manufacturer is not recommended, unless you upgrade your wheels to the proper width to accept the larger or narrower tire size. Let us explain.

Wide Motorcycle Tires on Narrow Rims:

Squeezing a 150mm tire (lets go back to that tire chart) … 150 = 6 inches onto a rim that was meant to accept a 130mm wide tire = 5.0 inches will pinch in the sidewall out and will cause an extreme arc in the side tread of the tire. This tire will now “fall very fast” into corners and will have much less of a contact patch, or rubber on the road in the corner. Not good!

Narrow Motorcycle Tires on Wide Rims:

This has the opposite effect of what we experienced above. We saw this when KTM and BMW both released bikes with a 170 rear tire and there were not but one or two tire choices. Lots of guys tried to run a 150 series tire and were sorely disappointed in the performance. Putting a 150mm tire 6” onto a rim designed for a 170mm or 7” wide tire completely flatten the tires profile.  This exposes the rim to damage and this tire will now take an extreme amount of pressure or force to lean into a corner and will be very slow to come out of the corner. In essence it will turn like a truck instead of like a nimble motorcycle.

  • *** Recommendation *** : Put the correct size tire on your factory or OEM wheels and if you have upgraded to aftermarket wheels, be sure to choose the correct size tier for your wheels, not what your owner’s manual “used to recommend.”

Tube or Tubeless Motorcycle Tires: What's the Difference?

This is a very common question. Most simply put, If you bike has spokes, you most likely will need a tube. If your bike has cast wheels, mag wheels, forged wheels or billet aluminum wheels you most likely be running tubeless tires as the inside of the wheel is smooth. There is no place for the air to escape, unlike spoke wheels. There are exceptions to this rule, like the BMW tubeless wheels, which run the spokes to the outside of the rim. Or the Yamaha Super Tenere wheels, with spokes that run to the center band on the center of the rim, just on the outside. These set-ups aside, most spoke rims have spokes, which protrude into the center of the inside of the rim, where the air sits, and these joints leak air. And therein lies the reason we used inner tubes. Tubes keep the air inside the tire / wheel from escaping. There are ways to make these wheels tubeless, but they often fail and can leave you stranded. Spoke wheels are meant to have tubes. Here are several other tube / tubeless related FAQ’s:Tire Tubes on Shelf

Can I run tubeless tires on a tube type rim?

Yes, any tubeless tire can be run on a tube type rim, as long as you fit a tube into the tire when mounting up the tire.

Should or Do I need to replace my tube at every tire change?

Yes and No…

    1. YES! On a street bike, which can see upwards of 20k miles between tire changes, we would totally recommend a tube change at every tire change! Who wants to “blow a tube” just a couple thousand miles into that new tire? Nobody!  Better to be safe than sorry.
    2. No, not really. On a dirt bike when you are putting only hours on a set of tires and the tire / tube do not get put to the same stresses of super high heat for hours, days or even months on end… If your tube looks good, run it again. We typically change our tubes out every three dirt bike tire changes or so… There is no science here… just a gut feeling.

What is the difference between a Regular Tube, a Heavy Duty Tube and an Ultra / Uber Heavy Duty Tube?

Standard Tubes are typically just over 1.2mm in thickness. Heavy Duty Tubes begin at 2.8mm and to up to 3.5mm depending on the manufacturer.Tire Tube Box

Ultra Duty or Uber Duty tubes are typically 4mm or more in thickness, depending on the manufacturer.

What size tubes do I need for my tires?

Back to the size chart, most tubes are sized in the Inch method. Example 3.25-19 tube will fit a 90/90-19 front tire or a MH-19 front wheel tire.

Are of the same sized (and thickness) tubes created equal?

No, now that we know what size tube we need, we need to look at what valve stems we need. Be careful, sometimes the front and rear wheels will require a different style of vale stem. Here are the questions that need to be answered when looking at valve stems:

    1. Is the Valve Stem center mounted or side mounted?
    2. Is the Valve Stem rubber or metal?
    3. Is the Valve Stem straight? Or does it have a 90 degree bend?
    4. Is the Valve Stem base threaded or non-threaded?
    5. Valve Stem Code : Most Common
      1. CMV = Center Metal Valve – Threaded Base with Nuts
      2. SMV = Side Metal Valve – Threaded Base with Nuts
      3. TR-4 (most common dirt bike) = CMV
      4. JS-87 = Center Metal 90 Degree Bend

Do I need a Rim Strip?

Yes, rim strips are very important. They keep your tube from getting rubbed or even punctured by the spokes where they come through the rim.

Balance Dots

Balance dots appear on most street oriented tires.  Balance dots are placed by the tire manufacture to indicate the lightest part of the tire. As a rule of thumb, when mounting the tire, it is best to line this dot up with the valve stem.  This should require “less weight” to be added in order to get the tire / wheel combo balanced.  All street or track bound tires should be balanced to ensure the best stability at speed, to promote even tire wear and to maximize mileage.

Motorcycle Tire Pressure

Running proper tire pressure is the single most important thing to check and to stay on top of once your tire is installed.  Most “Recommended Tire Pressures” provided by the manufacturer are clearly stated on the sidewall of all tires and state a “Max Load XXX lbs at XX PSI Cold.”  Another common reading would be “Maintain XX PSI.” Depending on the load you carry or the style of riding you do, tire pressures can be adjusted down to meet your needs, but never adjusted higher than the manufacture supplied recommended tire pressure.  NOTE: Running a decreased tire pressure will potentially cause uneven and premature tire wear.  To get the most out of your tires, stick with the manufacture’s recommended pressures.  Check tire pressures often with an accurate tire pressure gauge.

Choose the Proper Tires for Your Motorcycle

Motorcycle tires, second only to motorcycle brakes are one of the most important safety items on any motorcycle. Making sure you are running the proper tires on your motorcycle will ensure that you will have the best ride possible with your preferred outcome. Softer tires if you want to stick to the road. Harder tires if you want more mileage. Knobbier tires if you want to venture further off-road.

Chaparral Motorsports has the proper tire for any motorcycle on the road today.  You can shop the best priced tires on-line at ChapMoto.com, you can call our 800 number 1-800-841-2960 or you can visit our 160,000 sq-ft retail showroom.

Comments
  • Kinga Peter
    I'm a Kenyan with a street bike of tire sizes; front 90/90-17 M/C 49S and rear 120/80-17 M/C 61S. How can I get these tyres from you guys. Do you operate in Kenya? Kindly waiting for your response.Thanks
    • Eric Ellis
      Hi Kinga, you can place an order online via our website at chapmoto.com. Simply find the tires that you want and you can make the purchase through the website. Thanks. Ride safe.
  • Robert
    Question: Do you have a list of dual sport tires by weight?

    Thanks
    • Eric Ellis
      Hi Robert, sorry we do not have a list, however, if you visit Chapmoto.com the sort through our dual sport tires,when you click on a specific tire the bottom of the page has the specifications. Click on that tab is it will show you that specific tire's weight.
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