You’re called a “Dark sider” when you mount a car tire or more appropriately a passenger vehicle tire on the back of a motorcycle. The phrase is also used for a video game you can play on the PC, Playstatopn 3 & 4, Xbox 360, Xbox One and Wii U. I know nothing about Darksider the game series. But I have a little knowledge now about the act of running a car tire on the rear of a motorcycle. Specifically on the Yamaha FJR 1300 ES.
With the upcoming Iron Butt Rally to be held this summer, I’ve been pondering how I would get through the event without a tire change. You see, the FJR loves to eat my favorite tire of choice, the Michelin PR4. The best I could get out of one is around 10,000 miles. That will likely be 1,000 miles or more, short of the expected mileage for this summer’s event. So what to do…. I could just arrange to have a tire change done at one of the two check points but that would require me to get into the area early to reach a shop before they closed. If the check point was in the Houston area I MIGHT consider that but even then it would be unlikely. The next option would be to purchase a spare rim and mount a new tire ahead of time and have it delivered to the checkpoint. I could then change the complete rear wheel during a check point at the expense of rest time. Finally, there’s the option of mounting a passenger tire a.k.a. a car tire, on the motorcycle rim and not worrying about a tire change at all since these tires typically get 25,000 to 30,000 miles on them. I’ve even seen pictures of 32,000 mile tires that I probably wouldn’t have taken off unless I was going on an extended long ride like the IBR.
So last week I had a quiet afternoon and I took the opportunity to take off my fresh new PR4 with only 2,000 miles on it. I had a little difficulty with my NoMar tire changer and the new General G-MAX AS-03 205/50ZR-17 until I figured out that I needed to use my Posi-Clamps to get better clearance below the rim. Then the tire virtually fell on. Fabricating a new brake arm was as easy as drilling two holes in a piece of flat bar and painting it.
This morning I had the rare opportunity to be responsibility free so I could go for a ride. I took the bike out on my regular 100 mile “shake down” route. I like to use this route for anything I add to my riding setup. It’s long enough to help me identify problems, but close enough to the house that I don’t have to suffer when things aren’t working or need changing. The route has a mix of urban stop lights, interstate and back country roads with plenty of twists and turns.
Before embarking on this idea of going against the motorcycle tire status quo, I talked to several riders who had already made the switch. I listened to their opinions and comments about the choice. The general consensus was that it would take about 500 miles for me to develop the muscle memory of the differences. I don’t consider myself any sort super rider but it took less than 100 miles for me to get perfectly comfortable with this new set up.
First thing I had heard was that a car tire makes the motorcycle handle funny at low speeds. As I left the drive way I noticed it required slightly more handgrip pressure to weave back and forth. It felt as if there was a spring trying to return me to straight up vertical. After a stop at the nearby gas station for fuel and a few more turns the sensation seemed to disappear. It didn’t feel any worse than riding on a worn tire that had seen really long stretches of Interstate.
The next thing was “tracking” while going down the road at freeway speeds. I’d read some engineer types talking about how the large, flat surface of the rear tire would make the bike track funny. Well guys, put your slide rules and scientific calculators away. The bike tracked just fine at my normal cruising speeds on the highway. In fact, I noticed with the cruise control set, it was even easier to ride hands-free for longer periods of time.
What about cornering? Surely I wouldn’t be able to corner like I could on a motorcycle tire. I evaluated this from two points. First, how did it feel when I was in a corner? And was it confidence inspiring or the opposite? I was quite pleased to discover that cornering wasn’t really affected EXCEPT!!!! Back in my MSF instructor days, we always taught students to keep a steady throttle through corners because when you rolled off the throttle the bike wanted to stand up. That was in the curriculum but personally I felt like when you rolled off or chopped the throttle, the bike wanted to fall down. That was the sensation I experienced anyway. With the car tire, when I rolled off in a corner, it definitely wanted to STAND UP! At first, I noticed the increased and sustained handgrip pressure through corners. However, after riding through a few sweepers I realized the increased pressure wasn’t all that great. In fact, I discovered I could set the cornering line and take my hands off the grips (with cruise set of course) and the bike would follow through the corner. So much for needing a rounded motorcycle tire to keep a rider going through a corner successfully.
There was one exciting thing I noticed about the new tire though. When I got into some deeply grooved payment in a construction zone, the bike struggled to track. it was exciting. The larger rear tire seems susceptible to debris and even the lane markers more so than regular tires. I was happy to find out that transitioning up and down uneven pavement layers in construction zones wasn’t any different than on a regular motorcycle tire.
My conclusion…. this is going to work just fine for me this summer. If I was taking the bike to a track day or a Lee Parks performance riding class, I’d put on a motorcycle tire. But for street riding like we do in the long distance community this is just fine for ME. You might be different. After the IBR, I’ll probably leave the tire on until it wears out. After that I’ll likely put that slightly used PR4 back on and wear it out. Afterwards, it’s anyone’s guess what I’ll do. Geeesh! It’s at least 37,000 miles from now