by John Lloyd BMW MOA #236695
Published in BMW Owner’s News, October 2024
Anyone who knows me will tell you I am anal when it comes to my tires, especially on my motorcycles. I will often change out my tires in springtime in Florida, before the rainy season begins, so that I am confident I have the best available tread, should I get caught in a pop-up thunderstorm. Oftentimes, I will retire a tire once 50% of the tread has been worn. Is this wasteful? Perhaps, but having fresh tires gives me the confidence to ride to my limit, without worrying if I have enough traction.
In my opinion, tires are even more important than brakes, though perhaps only marginally so. If you lose brake pressure, you may still have options, time permitting. Hopefully, since the front and rear brakes are independent, you will still have some braking power from the remaining system. You may be able to coast to a stop, or even use engine braking. But, in the event of tire failure, all options are out-the-window. Maybe I have enough skill to bring the bike safely to a stop. But I don’t want to test those limits. Better to avoid a bad situation through good maintenance.
Tire Pressures
The most important measure of tire readiness is pressure. Incorrect tire pressures are very unforgiving on a motorcycle and can easily lead to a wobble and potential loss of control. Tire pressure is measured when the tires are cold, that is, before riding, since, tires get hotter due to friction between the tire and road, which exhibits greater pressure. On American touring bikes, the typical front and rear cold tire pressures are 36 front and 40 rear. Check your owner’s manual or look for a sticker, usually on the left side of the swingarm, for correct tire pressures for your bike. It is equally important to ensure that any replacement tires for your motorcycle match the original manufacturer specifications.
Tire pressures should be measured every day before you ride, as part of your pre-ride inspection. However, it is the minority of riders who adhere to this strict schedule. Alternatively, a tire pressure monitoring system (TPMS) can be a simple and relatively inexpensive alternative to getting down on the garage floor in your clean riding gear before each ride. TPMS technology can communicate with smartphones via Bluetooth for easy pre-ride and continuous tire pressure monitoring. Remember that tires will ‘leak’ some pressure over time, so checking your pressures regularly, especially during season changes is of critical importance.
Tread Depth
The purpose of tread on tires is displace water and small debris so that the tire and road maintain good contact. If you can personally guarantee that your bike will never see water, or debris, such as on a track, then tread depth may be less important. For the rest of us, tread can be critical.
New motorcycle tires have a tread depth of about 8/32nds (6mm in metric units), while the legal minimum tread depth in the US is 2/32nds (1.6 mm). By the time my tires tread depth falls below 5/32nds I am making plans for replacement because, in my experience, the wear is not linear. In fact, I find that the first 50% of tire tread lasts about 70% of the tire life, while the remaining 2 to 3 32nds will disappear quite quickly.
Tire Age
Raise your hand if you know how to check how old your tires are? On the tire sidewall you will find a Tire Identification Number (TIN). The last 4 digits of the TIN are the manufacturing date code, expressed in weeks (first 2 digits) and year (last 2 digits). For example, if the last 4 digits of the TIN are 0117, this would indicate that the tire was manufactured in the 1st week of 2017.
Personally, even if I have not ridden one of my bikes enough to warrant replacement based on tread wear, I will change out the tires if they are more than 3 years old, based on the manufacture date code. This is because tires deteriorate with age, which is unavoidable. Can you ride on tires that are older than 3 years? Sure. I may be anal, but have never experienced a situation on the road due to tire failure and would like to keep it that way.
Tire Replacement
Don’t expect four-wheeler like performance from your motorcycle tires. These are much softer than car tires and wear out far quicker. Unless you are running hard compound tires, which I don’t really recommend, you will be lucky to get more than 10,000 miles out of a bike tire. In my experience, though dependent on your riding style, rear tires will wear out about twice as fast as the front tires, due to the fact there are greater forces acting on the rear tire, as this is the drive wheel.
It is not necessary to replace both tires at the same time, unless needed. If the tread wear on the front is still fine, but the rear is looking a little tired, you don’t need to pay for both. Personally, I prefer to have matched tires front and rear, but that is just my preference. You will do your own research to determine which manufacturer and model tires match your riding style.
Motorcycle tires are made with a higher level of precision than car tires. Off the shelf they have minimal irregularities, unlike the road surface. However, there may be a release agent on the skin of a new tire, which is necessary to remove the tire from the mold. This release agent has a lower coefficient of friction and until that skin is scrubbed off, with careful riding, can cause unexpected sliding. It is therefore important to ride with more caution during the first 50 to 100 miles after a tire has been replaced. Don’t be the squid that tries to show off to the crowd doing a burnout from the dealership after getting their tires replaced, and ends up on the ground with egg on their face.
Reading your Tires
One can also tell the riding style and proficiency of a motorcyclist based on the tire wear patterns. Take a look at the following two images of very different tire wear patterns, both from sport bikes. The photo on the left is the front, yes front tire of a GSXR, which illustrates that the rider was quite comfortable and confident with their ability to lean the motorcycle. Whereas, the center portion of the rear tire on the right image is worn all the way to the cords, while the outer portion of the tire is mostly unused, indicative of mostly upright riding with little leaning.
Don’t make the mistake of trying to compare the wear patterns on your tires to those of another rider, since each rider’s style is unique. However, you can visually inspect and compare your wear patterns from photographic records as a measure of improvement in your own riding skills. Practice is key. When the opportunity presents itself, or at least every few weeks, go to a parking lot and practice in the safety of an open space.