Motorcycle Tires: What You Should Know
Let’s face it — at best, most of us have a passing understanding of our motorcycle tires. We spend only enough time on them to keep riding, but we want to keep riding on them all the time.
Most of us have to kind of force ourselves to check the air pressure as often as we should — and even that will go out the window as soon as most bikes start coming with tire pressure sensors. That said, here are some quick points to know about motorcycle tires – tips that will keep you safer and riding longer.
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Though modern motorcycle tires are manufactured to very high performance and durability standards, taking them for granted is a mistake. And assuming they are all alike or basically the same as tires for your car, is not right. Motorcycle tires are unique and absolutely critical to your safety and long-term enjoyment of your motorcycle.
Here are some of the key things to know about motorcycle tires.
1. Tires that appear to be the same can be very different in terms of how they are designed to be used safely. One of the key factors in this age of superbike performance bikes is the speed rating.
This is the letter (alphabetical) code number at the end of the tire size code imprinted on the sidewall of the tire, for example: in the code 120/90B-19 60 H, the “H” means the maximum safe speed rating is 130 mph (210 km/h). Here is a table of the speed ratings:
Code Max. speed (mph) / (km/h)
- L 75mph / 120kmh
- M 81/130
- N 87/140
- P 93/150
- Q 99/160
- R 106/170
- S 112/180
- T 118/190
- U 124/200
- H 130/210
- V 149/240
- W 168/270
- Y 186/300
- Z >149/>240
2. The majority of motorcycle tire sizes are expressed in metric dimensions.
Those dimensions and other information must be molded right into the sidewall of the tire. Using the same example above, 120/90B-19 60 H, here’s what the dimensions mean:
- “120” is the section width or the overall width of the tire in mm when installed and ready to ride.
- “90” is the aspect ratio, which is the expression of the sidewall height from the tread to the bead of the tire as a percentage of the section width. In this case, it is 90 percent of 120 mm or 108 mm.
- “B” indicates that the tire is of bias-ply construction; an “R” indicates it is a radial.
- “19” is the rim size diameter in inches.
3. In addition to the speed rating, there is a code for the safe maximum load called the “load index.” In this example,“60” is the load index rating code, meaning the maximum load rating code means 551 pounds.
Here’s a table of the DOT load index codes:
4. Each motorcycle is designed from the ground up with specific chassis specifications and suspension components that are intended to maximize handling, braking and stability with a specific type of tire in mind.
Changing from bias ply to radial tires or vice-versa may adversely affect the handling of the bike, so don’t make that kind of change without consulting a professional on it.
5. Never mix bias ply and radial tires on the same bike — as with point 4, the bike’s handling could be adversely affected. I’m not sure why anybody would ever do this, but I have heard of some folks doing it — never use automotive tires on a motorcycle, even if the size seems to fit.
6. Staying with the same type and size (even if by a different manufacturer) as was specified as original equipment (OE) for your bike is the easiest way to assure consistent performance.
Going with wider tires to try to increase cornering performance, for example, may cause interference between the tire and suspension or driveline components.
7. Racing tires, while designed for high stress, high performance applications, don’t necessarily make good street tires. This is because they are designed to function best at the higher tread operating temperatures than will occur in normal street riding.
Also, high-adhesion racing slicks lacking rain grooves of normal street tires may perform poorly in wet riding conditions.
8. Consider tread pattern in selecting tires because the tread pattern, the size and positioning of rain grooves affects how well the tires perform under the diverse road conditions encountered out on the road.
9 . Monitor the condition of your tires carefully. Bulges in the sidewall or tread most likely indicate a ply separation inside the tire and a catastrophic tire failure could be the result.
External damage such as cuts or cracking in the tread or sidewall should be checked out; while so-called “dry cracking” in the rubber of the sidewall may not indicate deeper tire damage, a split in the rubber down to the cord in one spot may indicate impact damage inside the tire. Check the rim for deformation or cracking if this type of damage is present.
10. The old saying is that “the tire doesn’t carry the load—the air does.” The point there being that maintaining proper tire inflation is crucial to proper performance, tire service life and safety.
Under-inflated tires overheat, are more prone to blow-outs, sidewall failure and premature wear. Similarly, over-inflated tires may fail prematurely and wear improperly.
Whatever you ride and wherever you ride, tires are the thing hooking you up to the ground, so take good care of them. Check your motorcycle tires before every ride, and be careful out there!