Definition
If you are reading this and you don’t already know what the Darkside is, I am honored to be able to introduce you to this topic.
First, let me say that this topic is as controversial as politics, religion, and the best oil. This topic is car tires on a motorcycles. Darksiding is not for everyone. We who are on the Darkside are going against the intended design of the tire/rim combo. My opinion is that Darksiding is only to be considered for large touring bikes with a lean angle of 45 degrees or less. But it’s your bike, do what you want.
If you want to view this information in a video format, check out this YouTube Playlist.
Why Darkside?
There are a lot of reasons people use a car tire. What usually gets people started is the cost savings. If you ride a lot of miles, you get tired (pun intended) of changing tires and paying for tires.
Why did the motorcycle take a nap? It was two tired.
So after spending a lot of money on tires people start looking into this Darkside thing. You come for the cost savings, but you stay for the benefits.
What are these supposed benefits?
Better braking.
Do you remember how you were taught to brake? Straighten then brake. If you are straight on a car tire, you have a much larger contact patch. Better braking.
Better wet weather traction
This one is more debatable and may be more related to the last one. But these multi compound tires are rather hard in the center and not always very sticky. So a great touring tire may not be great in the wet, but a car tire doesn’t have this problem. This was my experience using the Dunlop Elite 4’s. Wet weather wasn’t great, and I lived in the Pacific Northwest at the time.
Grooved pavement or grated bridges.
Motorcycle tires with their smaller contact patch can get caught following the lines in the concrete, milled roads, or grated bridge. This situation can be scary, or at least annoying. Car tires are wide enough to not be bothered by this very much. I have heard some large bikes, a Harley Fatboy, has large enough tires so this may not be an issue, but it was an issue on my Goldwing.
Runs cooler
More air in the tire means better cooling, better cooling should mean better wear. This is more theoretical to me, I’ve not studied it.
Better weight capacity.
Now we’re getting to something good. If you are on a large bike, many tires are barely stout enough for the bike itself, let alone a heavy rider, a passenger and a trailer. Check the weight ratings on your motorcycle tire to be sure it can handle what you are giving it. My car tire by itself can handle around 1100 lbs.
I’ve seen when people start towing the rear tire wears much quicker and sometimes they even have blowouts. Darkside for the win!
Is the Darkside right for you? You have to answer that for yourself.
Who Darksides?
I avoided Darkside, mainly due to the tire bead issue, see here for more info. I was convinced to try a car tire in part due to some YouTube videos I watched of someone else’s experience on the darkside—that of Chris Caliente.
There are a lot of other YouTubers who darkside.
- Brother Cowboy – Goldwing
- Motard Squid – Adventure bike – Multiple – Super Tenere, FJR
- Slappy Adventure’s
- Yogi’s Cycle Service
There are a number of Facebook groups that share their experiences and questions. If you’re on Facebook search Darkside and see how many groups and pages you can find. I’m a member of a few of them.
Another reason I was convinced to switch to the dark side is because many Iron Butt Riders ride on the Darkside. Iron Butt Riders are a group of people committed to safely traveling a large number of miles. My thought was, if they can ride those distances safely, then there must be something to it.
Do you ride Darkside, or have a favorite YouTuber who does, please comment and let me know.
What Do Critics of the Darkside Say?
This section has a great video that can be viewed here.
What gets me about most critics is they don’t have personal experience.
Many people say, “I’m sticking to what the engineers designed for my vehicle.” This is a good safe decision, but it shouldn’t be forced upon others. Many of us like modifying and hot rodding.
Another common concern is related to Insurance. But, Scott at GoldwingDocs has a video that talks about this issue and he addresses the insurance issue well.
Fortnine is an exception to the critics not trying it out. Ryan put a car tire on a BMW GS 700. This video has received over 3.7M views.
First issue I have with what he did, is that he picked a light bike to use the car tire.
I found that the tire I use on my Goldwing is the same tire used on a 2010 Mini Cooper.
Mini cooper weighs about 2500 lbs. Divided by 4 – 625, which is about 300 lbs less than my entire Goldwing. Half would be about 460 lbs which is only 166 lbs different. I’ll call that similar, especially when I have the bike loaded. For completion, the tire is rated for 1201 lbs.
One day I may dig deeper into what all this means, but I can tell you, I made a mistake in a curve, the tire kept traction until I started scrapping metal. You can check that video out here.
This get off was no more affected by the tire than by the gremlin bell. All that to say, I agree with Ryan. I don’t recommend this for lightweight bikes.
He did say he could hardly notice the difference after 10 minutes of riding. On a small bike.
Think about that. A very short time to adjust on what I call an inappropriate bike. There are plenty of people out there with the light bikes Darksided. Nothing wrong with it. I’m just saying on the large bikes, it’s a great choice.
Ryan mentioned something about spontaneous uninstallation. This is a great term, but it has never happened. I even had a flat on a non-runflat and the tire did not spontaneously uninstall.
The Bead surface was my concern that kept me from going Darkside for so long, but the TSA (that’s Traffic Safety Administration) statistics have no failures documented.
My experience is that it isn’t easy to break the bead either. I’ve changed a few car tires on my motorcycle rim, and it is never “easy.”
Poorer handling was a concern Ryan brought up, but he also said he didn’t notice the difference. So how bad was it?
I do need to hold in a curve with more force, but large bikes kinda need this anyway.
Riding off-road is no good for me with the car tire, but larger bikes don’t like offroad anyway.
Ryan did conclude the video saying the great mystery of Darkside is there should be no mystery that some of us risk doing it. “Let it go.”
Yup, we are out here doing it. I have over 50,000 miles on the Darkside. On a Goldwing. Like Brother Cowboy says, “I ain’t never going back!”
How to Go Darkside
So maybe you’re convinced that the Darkside is worth a try. Here are nine (9) steps to joining the Darkside.
Step 1. Type of bike
Light bikes can use a car tire, but it’s not optimal, see above. I recommend D arkside for heavy bikes for the increased load rating and the comfort the car tire brings
Step 2. Lean angle
If your bike’s lean angle is under 45 Degrees you will have plenty of tread and no worries of riding on the sidewall, more about sidewalls in step 8.
Plenty of people put a car tire on a bike with more than 45 degrees of lean angle. I’m talking about what I think is optimal.
Step 3. Determine the equivalent car tire size
Now it’s time to determine the equivalent car tire size.
There used to be a great website that would tell you what car tire fits on your motorcycle. I don’t know what happened to that site. Leave a comment if you know.
My Goldwing Motorcycle tire size is 180/60-16 and my car tire size is 195/55-16. I’ve placed the discussion on how to calculate after these steps.
Step 4: Choose run-flat or not.
I’ve been told that when dealing with a flat tire, the run-flat tire is not as scary, but it’s still not a pleasant experience. I had a flat on a non-run flat and I wouldn’t want to do that again.
My experience says the stiffer sidewalls of the run-flat is similar to the ride of a motorcycle tire, while the non run-flat has a softer ride. Choose your own adventure here, but I recommend the first car tire you use on your motorcycle be a run-flat.
Step 5: Find what tires others are using
You can skip this step, but it’s always good to see what others are saying. This is why I started with the Bridgestone Driveguard – Chris Caliente had good things to say about it. Once I wore that tire out, I changed to a Kumho Majesty 9 non-runflat because I found it on sale and I didn’t see anyone else using it.
Yes, sometimes I do things because I haven’t seen anyone else do it.
Check out forums, like Goldwing Docs or GL1800riders, and other YouTube channels to see what people say about their car tire.
Step 6: Look at tires
Take your tire size and ideas of what others are using to the store, either online or brick and mortar.
I mainly use Discount Tires, but Amazon, TireRack.com, Sam’s Club, Costco and many others can be used. Search based on tire size, or if you have a 2001-2010 GL1800 you can say it’s a 2010 Mini Cooper.
Step 7: Look for rounded sidewalls
Other people’s experience is a great guide, but check that the sidewalls are rounded.
A Michelin Defender LTX M/S 2 is not rounded and would not be a good choice. Although I love this tire for trucks and SUVs.
Right now, I have a Pirelli Cinturato P7 on my bike. You need a rounded sidewall so you can hit those curves with confidence.
Step 8: Order your tire.
Often the tire I want is not in stock locally. So I can’t just run down and pick it up.
You can order at a place like my favorite, Discount Tire, or your favorite local tire store. You can even go to Walmart or Costco. There are a few online tire stores as well like TireRack.com
Step 9: Change your tire.
This should be the easiest step, but it’s not.
For my first Darkside tire in September 2018, I called up my favorite tire shop, Discount Tire, and asked if I brought my motorcycle tire and rim down if they would mount the car tire. They agreed and the appointment was set. I arrived and there were no issues, at first. When they were dismounting the tire their equipment broke the Tire Pressure Monitoring System sensor. We found a new part at a nearby Honda Dealership and they hid it in the bushes because I got it after hours.
But Discount Tires made it right and mounted my tire. However; they did not want to do it again. Sorry if you were counting on them being the shop to use. Your local one may, but they may not.
So I got my first car tire and I liked it. Check out this video for my initial reactions
But what would I do for my next tire? For now, I’ll leave it by saying, you may find a shop that will change it for you, but you’ll have better luck finding a friend with the right tools and experience to help you change it.
Some local shops may, and most dealerships will not, mount a car tire on a motorcycle rim. A possible exception is if you bring in the tire and rim and tell them it is on a trike.
What did I do? I ordered an Olmax Motors tool, see this video, to change them now.
In case you’re curious, Chris Caliente purchased serious equipment. See how cheap we Darksiders are? We spare no expense to buy cheaper tires. But seriously, my last car tire I purchased for my Goldwing cost about the same as a motorcycle tire. I don’t do this to save money, I do this because the car tires work better for me.
If you cannot find someone to mount the tire and are not comfortable doing it yourself, Darksiding may not be for you.
Tire Size Calculation
Now, let’s finish our math discussion for step 3: car tire size
This can be calculated by looking at your motorcycle tire size. I’ll use my Goldwing for an example.
2010 Goldwing rear tire size is 180/60 – 16
Last number is rim size, or the diameter of the tire in inches.
The first number is the width of the tire in milimeters
Second number is the sidewall height as a percentage of the width of the tire.
Car tires have the same placeholders, but not necessarily the same values.
A quick internet search of common car tire sizes with a 16 in rim provides me with these:
125, 135, 145, 155, 175, 185, 195, 205
None of these are 180 so I should look at tires around 185 or 195
Now, I look at the the sidewall percentages:
For 185 I find 50, 55, 60 and 80.
My Goldwing is 180 * 0.60, which gives me a sidewall height of 108 mm. This is the goal.
185 mm * 0.55 is 101.75 mm
185 * 0.6 is 111 mm
Neither is very close. I want the number to be close because that will keep my speedometer accurate.
Step up to a width of 195 and you’ll find a sidewall percentage of 55 works well and yeilds a sidewall height of 107.25 mm.
This is how to calculate the tire size. Warning: just because you found a common size doesn’t mean your favorite manufacture will make one in that size. I really like Michelin tires, but they don’t make a 195/55-16 tire. But others do.
50,000 Mile Darkside Review
When my dad and I were in Maggie Valley, we had a guy walk up to us because he noticed we both had car tires on our bikes. We’ll call this guy Kevin.
Kevin rides a Harley Fatboy and his brother-in-law suggested he go Darkside. It seemed as though he had his doubts about his brother’s sanity, but he noticed our insanity, and asked us about it.
There was a lot to say. My dad reassured him that a Fatboy was a great candidate for a car tire. Dad owned a Fatboy for a while.
I handed him one of my cards and told him I have a number of videos on this subject. Here’s the playlist link again.
I have ridden over 50,000 miles and am on my third car tire, a Pirelli Cinturato P7 run-flat.
To me, a run-flat feel just like a motorcycle tire. A non-run-flat feels soft and more comfortable. It really does make the Goldwing feel like a couch. If I were planning to ride primarily highways and interstates, I would use a non-run-flat. So nice.
Both tires take the scariness out of milled roads or grated bridges. Some motorcycles have wider tires and this isn’t much of an issue. Yes, I’m talking about you, Fatboy.
But the standard Goldwing tires love to try to follow the lines and isn’t fun. This was a big reason Chris Caliente came to the Darkside.
I did have one scary time with the darkside and grooved cement interstate. It was in a fast curve on the interstate and the grooves were not following the curve and even the car tire thought it was too much.
I get lots of questions about my car tire and my big get off. One person asked if the tire encouraged me to stand the bike upright. Could be. The tire held the road until I hit metal on the bike. So, grip wasn’t an issue. But even if the tire did encourage me to straighten, it was due to fatigue and so it was rider error.
My first car tire was installed when I lived in Oregon and I rode a lot of the Pacific Northwest prior to using the motorcycle to move to Georgia. Here is a playlist of my moving videos.
It was cool using a motorcycle to move myself across the country. But I am glad I’m here in Tennessee with my wife and kids.
I’ve done cross country, a couple of trips to Sturgis, I’ve ridden Iron Mountain Road, Beartooth Highway and many other great roads in that area. And, yes, a car tire does fine on the dragon, Cherohala, Blue Ridge, Natchez Trace and a bit of Arkansas, like the Pig Trail. 50,000 miles takes you to a few places.
When I got a flat in Arkansas the car tire plugged easily so we were only stopped in the heat for about 30 minutes. I’ve never tried plugging a motorcycle tire, but the car tire plug held for a couple thousand miles before I replaced it.
I pull my Lumina trailer around a good bit. I do enjoy that luxury and I feel confident towing knowing my car tire can more than handle the stresses.
There’s a few people with strong opinions against Darkside, but I like it and will keep doing it.
See you on the road!