Today we’re going to examine a very controversial subject: motorcycle tires and why they wear more on one side than the other. Tires and tire pressure are like oil; everybody has an opinion and will fight to defend it. So why does the outside of the rear tire wear down on the side?
The compound on the outer edge of the tire (front and rear) is softer than the middle. This means it will wear faster on the side you go faster on, especially if you live in the UK, as they ride on the right-hand side of the road and have more right-hand corners.
Today we’re going to approach this from a different angle. First, we will look at how you ride and what conditions you ride because this affects tires and tire wear.
We’ll start by looking briefly at tires, then riding styles and other factors that may influence tire wear. Then we’ll look at why the wear is more prevalent on one side or the other in different countries.
Remember, this is a layman’s view of motorcycle tires; we don’t go into great detail, and much of the information has been simplified.
I’ve been riding for about 40 years and earned my living on motorcycles. I spent two years as a dispatch rider in New York, riding in all weather.
In those days, we had bias ply, or cross ply tires, with, how can I put it politely, not very good grip.
I normally ride every day, and I ride about 16,000 miles, or about 25,000 kilometers, a year in virtually all weather.
I’ve analyzed what the tire professionals have said and written, then, most importantly, tested their advice, suggestions, and recommendations on my bikes in real-world situations.
So I know what works and, more importantly, what doesn’t work for me.
Before we get into the details, I need to stress that you make any changes from the manufacturer’s recommended settings totally and solely at your own risk.
Always ride safely and within the laws of your land. Right, that’s over with, so let’s get into the information.
As with everything, you need a known starting point, which you can easily return if necessary.
So let’s look at the starting point first, then we’ll go into your riding requirements and tire wear patterns.
The starting point is always the information provided by the motorcycle manufacturer, as stated in the manual.
This is because they have spent a lot of time, effort, and research on finding the best balance for the average rider.
Note, the average rider also because it’s an easy reference to find; it’s in the owner’s manual.
Most of us are average or below-average riders regardless of how we see ourselves, so why have the bike manufacturers settled on these pressures and suspension settings?
As stated above, it’s for balance in association with the tire companies. They looked at three main areas for the average rider, not the street rider, and struck a balance between them.
These are grip, comfort, and longevity. If you look at the swing arm and the owner’s handbook, you’ll find the tire pressure information. Suspension information is in the owner’s handbook.
For most bikes with 17-inch rims, the manufacturer’s recommended cold tire pressures are 36 psi front and 42 psi rear.
Are these the best pressures for you? Maybe, maybe not. We’ll look at this a little later.
“Cold tire pressure” is when the carcass of a tire is at the same or similar temperature as the surrounding air in the shade, and the air inside the tires is at the same or similar temperature as the air outside.
Okay, it’s nearly impossible to measure the temperature inside the tires unless you have an internal thermometer, so go by the temperature of the tire carcass.
As to the tires themselves, motorcycle tires are available for many different types of use and motorcycles.
Including sports, sports touring, touring cruisers, scooters, on-off-road dual sports, enduro motocross racing, etc.
Today’s tires for most sports and touring motorcycles are dual-compound radial tires.
There are other types of tires, but dual-compound radial tires are the most common for these types of bikes.
So what is a dual compound radial tire? A radial tire, more properly a radial-ply tire, is a designer tire where the cord flies inside the tire and is arranged at 90 degrees to the direction of travel, or radially.
Radial tires were invented in the early 1900s but never used, as far as I know, until Michelin designed and developed the first commercially available radial tire for cars in 1946.
Motorcyclists had to wait until 1983 before Pirelli introduced the MP7 radials for the Honda VF-1000R.
Note: Today’s tires are usually made of synthetic rubber and polymer natural rubber, so what are the benefits of radial tires? Well, they run cooler and maintain excellent flexibility.
This allows the engineers to significantly increase grip and tread life under a broader range of conditions than the older bias ply cross-ply tires.
Dual compound tires have been available for motorcycles since about 2005.
Dual compound means that the center of the tire is made of a different, usually harder compound than the outside of the tire.
This has several advantages. The two most important things for ordinary riders are that the tire lasts longer and has more grip when leaning over, i.e., cornering.
Let’s look at who is the average rider.
- The average rider is of average weight, weighing approximately 75 kilos, or 165 pounds.
- The average rider is of average ability. The average rider does an average amount of riding each year, three thousand to six thousand miles.
- They ride in average weather conditions such as temperature, precipitation, etc.
- They ride on average road surfaces, sometimes very average road surfaces. They ride a balance of twisty and straight roads.
- They ride a balance of city and out-of-town roads. They ride at an average speed for the conditions.
- Their motorcycle is set up with the average suspension settings suggested by the manufacturer.
- The tire pressures are usually set to the recommended, so that is an average rider.
If any of the above does not apply, you must adjust the manufacturer’s recommended pressures and suspension settings, either up or down.
The sixty-four thousand dollar question is: what adjustments do I need to make? Only you can answer that, as it depends on too many factors. You will need trial and error to see what suits you best.
Always make small incremental changes and test thoroughly. For example, you might increase the front tire pressure by one psi and test thoroughly.
Is it better or worse? Is the grip better or worse? You get the idea.
I always use an accurate tire pressure gauge and have an easy-to-use tire pump. In addition, I use a rechargeable tire pump, which has an accurate gauge.
It is easy to use and allows you to quickly and easily check and adjust the air pressure in your tires.
Remember never to make too many changes at once, as this can make it harder to pinpoint which change was for the better.
Okay, let’s focus on the other criteria affecting your setup.
There are three sections to this:
- What type of riding do you do?
- Do you take trips on the highway?
- Do you ride to meetups?
- Do you ride to work?
- Do you like riding the twisties and the canyon carvings, or do you prefer track days?
How do you ride? Is it a gentle highway cruising at 60 to 70 miles an hour under 110 kph, or a high-speed highway riding above 80 miles an hour?
Do you ride just normal roads, nothing aggressive? Just general daily riding, normal commuting, canyoning, twisty roads.
In what conditions do you ride? For example, do you ride in a cold or temperate climate, i.e., not too hot or too cold? Do you ride in all conditions?
Do you only ride in the dry? Do you ride in blistering hot temperatures, like in the desert near the equator or in arid conditions?
Each of these will require different pressure and setup for your motorcycle. If riding in all conditions, etc., you should be close to the manufacturer’s settings.
The majority of items are higher. Increase the psi by one psi at a time, and then check thoroughly. Most items lower the psi by one psi at a time until you find the right settings for you.
The rear tire requires less adjustment, except for very aggressive riding than the front.
Always check your pressure with cold tires. That’s very important as tire pressure can rise between three and seven psi when the tires are hot.
Remember that the pressures will also change slightly with the seasons and external temperatures.
Where I live, we can see a 15-degree Celsius (27 degrees Fahrenheit) difference between morning and afternoon temperatures.
Check pressures regularly, weekly is good, and every time you ride is better. Using the pump I mentioned before makes it very easy.
There are a lot of variables here, so you will need to use trial and error to find the best pressures for you.
Now to the crux of the matter. Why do my tires in the Americas, most of Europe, etc., were more on the left and tires in the UK, Asia, Australia, etc., more on the right?
If you said they drive on different sides of the road, you’d be right, but why is this not as urban myths have it, to do with the crown or the camber of the road?
This is because usually, the crown or the camber isn’t pronounced enough to have any effect, or if it did, it would be very slight indeed.
The real reason is to do with the corners themselves if you drive on the right (in the USA, most of Europe, etc., left-hand corners are much more open, and you can see further around the corner.
You can position the bike differently, and you have more space to use the width of the road if necessary safely, so you tend to take those corners faster.
On the other hand, right-hand corners are tighter, and you can’t see as far around the corner. So you tend to take those corners more slowly. In the UK, Asia, etc., they drive on the left, so it’s the opposite.
Right-hand corners are more open, and left-hand corners are more closed, so why does taking corners faster matter?
Well, the faster you go, the more heat you generate in the tire. The faster you go, the more grip is used, and the more of the tire you are wearing away.
So when you combine the two, heat and grip, the tire wear is greater in a corner.
There are a lot of myths floating around, so always seek reputable advice about tires and suspension.
Talk to tire technicians at the track, and get information from tire representatives or the tire company’s websites.
Be very wary of anything anyone suggests, including them, until you can verify the information independently one way or another.
I’ve seen, watched, and heard some bad information and advice from so-called experts. Some of it was convergent on criminally dangerous. So never go on trust alone.
Remember, this is a general layman’s guide, and you make any changes from the manufacturer’s recommended settings totally and solely at your own risk.
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